Pelagic Fish Surveys of 20 Lakes in Northern British

Pelagic Fish Surveys of 20 Lakes in Northern British
Pelagic Fish Surveys of 20 Lakes in Northern British
Columbia From: 2006 to 2009
S.G. MacLellan and J.M.B. Hume
Salmon and Freshwater Ecosystems Division
Science Branch, Pacific Region
Cultus Lake Salmon Research Laboratory
Fisheries and Oceans Canada
4222 Columbia Valley Highway
Cultus Lake, BC
V2R 5B6
2011
Canadian Technical Report of
Fisheries and Aquatic Sciences 2950
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Canadian Technical Report of
Fisheries and Aquatic Sciences 2950
2011
PELAGIC FISH SURVEYS OF 20 LAKES IN NORTHERN BRITISH COLUMBIA
FROM: 2006 TO 2009
by
S.G. MacLellan and J.M.B. Hume
Salmon and Freshwater Ecosystems Division
Science Branch, Pacific Region
Cultus Lake Salmon Research Laboratory
Fisheries and Oceans Canada
4222 Columbia Valley Highway
Cultus Lake, BC
V2R 5B6
© Her Majesty the Queen in Right of Canada, 2011.
Cat. No. Fs 97-6/2950E ISSN 0706-6457
Correct citation for this publication:
MacLellan, S.G. and Hume, J.M.B. 2011. Pelagic fish surveys of 20 lakes in Northern British
Columbia from: 2006 to 2009. Can. Tech. Rep. Fish. Aquat. Sci. 2950: viii + 139 p.
ii
TABLE OF CONTENTS
LIST OF TABLES......................................................................................................................... iv
LIST OF FIGURES ........................................................................................................................ v
LIST OF APPENDICIES .............................................................................................................. vi
ABSTRACT.................................................................................................................................. vii
RÉSUMÉ ...................................................................................................................................... vii
INTRODUCTION .......................................................................................................................... 1
THE STUDY LAKES..................................................................................................................... 2
METHODS ..................................................................................................................................... 2
FIELD DATA COLLECTION................................................................................................... 2
Fish Sampling ..........................................................................................................................3
Hydroacoustic Sampling ..........................................................................................................3
Zooplankton Sampling.............................................................................................................4
SAMPLE AND DATA PROCESSING ..................................................................................... 4
Hydroacoustic Methods ...........................................................................................................4
Fish and Diet Samples .............................................................................................................5
Zooplankton Samples...............................................................................................................5
RESULTS AND DISCUSSION ..................................................................................................... 5
LAKE CLASSIFICATION ........................................................................................................ 6
BIASES IN SAMPLING EQUIPMENT.................................................................................... 6
FISH SPECIES COMPOSITION AND SIZE............................................................................ 7
Pelagic Fish Composition - Trawl and Gill Net Samples ........................................................7
Hanging Lakes – Fish Composition.........................................................................................8
HYDROACOUSTIC ABUNDANCE ESTIMATES ................................................................. 9
DIET ......................................................................................................................................... 10
PLANKTIVORE BIOMASS AND PREDICTED PRODUCTION ........................................ 11
WATER CLARITY SUMMARY ............................................................................................ 12
ACKNOWLEDGEMENTS.......................................................................................................... 13
REFERENCES ............................................................................................................................. 14
APPENDICES .............................................................................................................................. 81
iii
LIST OF TABLES
Table 1. Location and morphological data for each of the study lakes. The number of
trawling sections and acoustic transects are shown…………………...……………….….
17
Table 2. Fish caught by midwater trawls and gill nets in lakes of different water types.
CPUE was determined by dividing total catch of each taxa by total trawling time in each
water type. CPUE for gill nets was based on overnight sets………………………….
18
Table 3. Catch and size of O. nerka caught in the trawl and gill nets in the surveyed
lakes. Gill nets were small meshed Swedish nets, except where indicated………………
19
Table 4. Catch and size of other fish species caught in the trawl and gill nets in the
surveyed lakes. Gill nets were small meshed Swedish nets, except where indicated……
24
Table. 5. Mean length of commonly caught pelagic fish species from sockeye rearing
lakes for each water type. Hanging lakes are not included………………………………
29
Table 6. Size of fish caught with other gears from the surveyed lakes…………………..
30
Table 7. Estimated abundance and biomass of juvenile O. nerka and dominant
competitor fish species in the study lakes. Density estimates are from Appendix 3. Size
estimates are average weight of formalin preserved juvenile O. nerka (age-0, Age-1 and
sometimes age-2) from Appendix 4………………………………………………………
31
iv
LIST OF FIGURES
Fig. 1. Overview map of study region showing the location of the surveyed lakes…..
33
Fig. 2. Maps of the study lakes showing the location of transects; a) Alastair, b)
Batchellor, c) Bowser, d) Elbow, e) Fred Wright, f) Keecha, g) Kimsquit, h) Kitlope,
i) Koeye, j) Kooryet, k) Kwinageese, l) Lonesome, m) Meziadin, n) Moore, o)
Morice, p) Namu, q) Red Bluff, r) Tankeeah (lower), s) Tankeeah (upper),
t) Whalen……....………………………………………………………………………
34 - 53
Fig. 3. Bathymetric charts of the study lakes created from the hydoracoustic survey
soundings; a) Alastair, b) Batchellor, c) Bowser, d) Elbow, e) Keecha, f) Kimsquit, g)
Kitlope, h) Koeye, i) Kooryet, j) Moore, k) Namu, l) Red Bluff, m) Tankeeah (lower),
n) Tankeeah (upper)……………………………………………………………………
54 - 67
Fig. 4a. Length frequency of all O. nerka caught during September surveys (17
lakes) using the small trawl and Swedish gill nets. Eight larger kokanee (>180 mm)
caught by gillnets are not displayed. Data was grouped into 3 mm length bins for
plotting………………………………………………………………………………….
68
Fig. 4b. Length frequency of all O. nerka caught during September surveys (17
lakes) using the large and small trawls. Data was grouped into 3 mm length bins for
plotting………………………………………………………………………………….
68
Fig. 5. General components of the diet of age-0 and age-1 O. nerka averaged for each
of the 3 lake types by abundance and by biomass. Diet data from this study and from
Hume and MacLellan (2008) were pooled for this analysis. The biomass of terrestrial
insects is not reliably measured. Macro-invertebrates includes Chaoborus,
Chironomid, and Ceratopogonid larvae, Neomysis, worms, and amphipods…………
69
Fig. 6. Zooplankton components of the diet of age-0 and age-1 O. nerka averaged for
each of the three lake types by abundance and by biomass. Diet data from this study
and from Hume and MacLellan (2008) were pooled for this analysis...........................
70
Fig. 7. Stickleback diet in stained and clear lakes. The values for stained lakes are an
average of 12 lakes, whereas the clear lake values are from only one lake (Alastair
Lake). …………………………………………………………………………………..
71
Fig. 8. Estimated abundance of prey items for age-0 O. nerka from lake surveys.
Includes lakes covered by this report and Hume and MacLellan (2008)…………........
72
Fig. 9. Estimated biomass of prey items for age-0 O. nerka from lake surveys.
Includes lakes covered by this report and Hume and MacLellan (2008)………………
73
Fig. 10. Length frequency histograms of O. nerka from each survey…………………
74 - 80
v
LIST OF APPENDICIES
Appendix 1. Individual lake reports……………………………………………………….
81
Alastair Lake………………………………………………………………………..
Batchellor Lake……………………………………………………………………..
Bowser Lake………………………………………………………………………..
Elbow Lake…………………………………………………………………………
Fred Wright Lake…………………………………………………………………..
Keecha Lake………………………………………………………………………..
Kimsquit Lake………………………………………………………………………
Kitlope Lake………………………………………………………………………..
Koeye Lake…………………………………………………………………………
Kooryet Lake……………………………………………………………………….
Kwinageese Lake…………………………………………………………………...
Lonesome Lake……………………………………………………………………..
Meziadin Lake………………………………………………………………………
Moore Lake…………………………………………………………………………
Morice Lake………………………………………………………………………...
Namu Lake………………………………………………………………………….
Red Bluff Lake……………………………………………………………………...
Tankeeah (lower) Lake……………………………………………………………...
Tankeeah (upper) Lake……………………………………………………………...
Whalen Lake………………………………………………………………………..
81
82
82
83
84
85
86
86
87
88
88
89
90
91
92
93
93
94
94
95
Appendix 2. Record of trawls and net sets completed during surveys of the study lakes…
97
Appendix 3. Hydroacoustic estimates of pelagic fish populations………………………..
111
Appendix 4. Summary of captured fish for each survey by capture gear, preservative,
and taxa…………………………………………………………………………………….
114
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from
surveys in Hume and MacLellan (2008)……………………………………………….….
121
Appendix 6. Late summer zooplankton densities and biomass estimated from 160 um
mesh, vertical haul, Wisconsin net samples. Haul depth was 30 m, except where
indicated…………………………………………………………………………………….
138
vi
ABSTRACT
MacLellan, S.G. and Hume, J.M.B. 2011. Pelagic fish surveys of 20 lakes in Northern British
Columbia from: 2006 to 2009. Can. Tech. Rep. Fish. Aquat. Sci. 2950: viii + 139 p.
We conducted pelagic fish surveys using hydroacoustics, midwater trawls and small
mesh gillnets in 20 sockeye (Oncorhynchus nerka) rearing lakes in the Nass and Skeena river
systems and in the north and central coast regions of British Columbia. We present the results in
relation to lake water type and provide detailed results for each lake. We detected differences in
vertical distribution, species composition and diet between clear, stained and glacially turbid
lakes. Clear lakes had the most diverse pelagic fish community but age-0 O. nerka (mostly
sockeye) were the most common species found. Glacially turbid lakes had far fewer species and
age-0 O. nerka were the most common. Threespine stickleback (Gasterosteus aculeatus) and
age-0 O. nerka were the dominant species in the stained lakes. Daphnia were the dominant prey
item of age-0 O. nerka in clear lakes while Bosmina dominated in the diets in stained lakes.
Copepods and terrestrial insects were the most common prey items in glacially turbid lakes.
RÉSUMÉ
MacLellan, S.G. and Hume, J.M.B. 2011. Pelagic fish surveys of 20 lakes in Northern British
Columbia from : 2006 to 2009. Can. Tech. Rep. Fish. Aquat. Sci. 2950: viii + 139 p.
En nous servant de la détection hydroacoustique, de chaluts méso-pélagiques et de filets
maillants à petit maillage, nous avons effectué des relevés sur les poissons pélagiques dans
20 lacs d’alevinage du saumon rouge (Oncorhynchus nerka) dans les réseaux de la Nass et de la
Skeena et sur les côtes centrale et nord de la Colombie-Britannique. Nous présentons les résultats
selon le type d’eau de ces lacs. Nous avons relevé des différences dans la distribution verticale,
la composition spécifique et l’alimentation entre les lacs aux eaux claires, les lacs aux eaux
sombres et les lacs glaciaires aux eaux turbides. Les lacs aux eaux claires renfermaient la
communauté de poissons pélagiques la plus diversifiée, bien que O. nerka, sous la forme
d’individus d’âge 0, était l’espèce la plus commune qui s’y trouvait. Les lacs glaciaires aux eaux
turbides renfermaient beaucoup moins d’espèces, mais O. nerka, sous la forme d’individus
d’âge 0, y était aussi l’espèce la plus commune. L’épinoche à trois épines (Gasterosteus
aculeatus) et O. nerka, sous la forme d’individus d’âge 0, étaient les espèces dominantes dans les
lacs aux eaux sombres. Daphnia constituait la proie dominante des saumons rouges d’âge 0 dans
les lacs aux eaux claires. Bosmina constituait l’élément dominant des régimes alimentaires des
poissons dans les lacs aux eaux sombres, alors que les copépodes et les insectes terrestres étaient
les proies les plus communes dans les lacs glaciaires aux eaux turbides.
vii
viii
INTRODUCTION
The effective management of sockeye salmon (Oncorhynchus nerka) stocks requires
reliable estimates of abundance, but sockeye salmon stocks along the central and north coast of
British Columbia and in the Skeena and Nass watersheds are many, tend to be small, widely
dispersed, and are often remote with difficult access. This combination of factors makes
traditional adult enumeration of spawning populations both expensive and difficult to conduct
from year to year. Pelagic surveys of juvenile sockeye salmon using hydroacoustics and trawl
nets offer an easier and cost effective alternative assessment method (MacLellan and Hume
2010).
The results of pelagic fish surveys of 23 sockeye salmon rearing lakes, surveyed from
1997 to 2005, in the Skeena River watershed and on the north coast of British Columbia were
reported in Hume and MacLellan (2008). In this paper we report on an additional 20 lakes
surveyed from 2006 to 2009. These lakes were located in the Skeena and Nass river watersheds
and on the north and central coast of British Columbia.
The primary objective of most of these surveys was to assess the stock status of the
sockeye populations and their competitors in the study lakes. We did this by estimating pelagic
fish abundance using mobile hydroacoustic surveys accompanied by midwater trawling and
gillnetting. However, three lakes, (Batchellor, Red Bluff and Whalen lakes), known as hanging
lakes, have waterfalls on their outflow creeks, which are barriers to anadromous fish passage,
and therefore had no existing sockeye populations utilizing the lake. The Gitga’at First Nation,
based at Hartley Bay, initiated a project to investigate the feasibility of using these hanging lakes
to rear sockeye fry in support of a terminal fishery on the returning adults at the mouth of the
outlet creek. Thus, our objective on these three lakes was to support the Gitga’at hanging lakes
study by collecting information on the existing pelagic and littoral fish populations of these
lakes, for the purpose of evaluating each lake for its suitability to rear out-plants of juvenile
sockeye.
While some lakes in this report and in Hume and MacLellan (2008) have been surveyed
previously, these are the first pelagic (acoustic and trawl) fish surveys of many of the lakes (28
of 42). In Hume and MacLellan (2008), the study lakes were divided into three different water
types; clear, dystrophic (stained) and glacial, where glacial was defined as a lake with any direct
influence by glacial melt waters. In this paper, we present the results in relationship to these
water types, but have modified the definition of glacial lakes to only include glacially turbid
lakes that have significantly decreased light transmission rates (Lloyd et al. 1987, see methods).
A number of lakes that were previously classified as glacial would now be classified as clear
using the new criteria.
THE STUDY LAKES
The 20 study lakes are located in five regions of British Columbia (Fig. 1, Table 1). Four
of the lakes are within the Nass River watershed and include Meziadin, Bowser, Fred Wright,
and Kwinageese lakes. All are located inland and sockeye migrations to and from the ocean
range from about 170 km to 250 km. Alastair and Morice lakes are both in the Skeena watershed
but differ greatly in climate and circumstance. Alastair is near coastal in nature, being only 45 m
above sea level, and a relatively short migration distance (70 km) from the ocean and is
frequented by harbour seals (Phoca vitulina). Morice on the other hand is well inland, at an
elevation of 763 m, and migrating salmon travel 425 km to get to this lake. Lonesome and
Elbow lakes are located in the Atnarko Valley in the interior Bella Coola region and are part of
Tweedsmuir Provincial Park. These lakes are approximately 100 km upstream of the ocean and
elevations are 485 m and 590 m respectively. Lastly, lakes in the north and central coast regions
of British Columbia are on the islands and peninsulas of the British Columbia coast. Typically
their outlets flow only a short distance to the ocean, often only a kilometer or two, and they are
subject to a maritime climate. On the north coast we surveyed Batchellor, Red Bluff and Whalen
lakes for the hanging lakes study, and Keecha, Kooryet, Moore, Kitlope and Kimsquit lakes to
assess sockeye stock status. On the central coast we surveyed Koeye, Namu, and the Tankeeah
lakes (upper and lower) to assess sockeye stock status.
Most of the coastal lakes were of the stained water type, with only Kitlope and Kimsquit
lakes being categorized as clear. All interior lakes were either clear or glacially turbid. Lake
size varied greatly, from Tankeeah Upper Lake at 129 ha to Morice Lake covering 9 738 ha. The
shallowest lakes were the two Tankeeah lakes with average depths of 8 and 10 m, while Whalen
and Morice lakes had average depths around 100 m. Moore Lake is at the lowest elevation of all
our study lakes at only 5 m above sea level, and has a saline layer in its lower basin starting at
about 20 m depth, suggesting possible periodic incursions of salt water from the ocean. The
highest study lake is Morice at 763 m above sea level. Pelagic fish densities range from a high
of 6 472 fish/ha in clear Alastair Lake to 39 fish/ha in glacially turbid Bowser Lake.
METHODS
FIELD DATA COLLECTION
We surveyed populations of pelagic fish using hydroacoustic and midwater trawling
techniques developed for juvenile sockeye salmon (Burczynski and Johnson 1986, Hume et al.
1996, Hyatt et al. 1984, Hume and MacLellan 2008, MacLellan and Hume 2010). In preparation
for each lake survey, we developed a survey design as in Hume and MacLellan (2008), but
increased the minimum number of transects per lake to seven, in order to reduce the variance in
the abundance and density estimates (Figs. 2a to 2t). Data and sample collection in the field was
done the same as in Hume and MacLellan (2008). Surveys were conducted in late summer and
2
early fall from September 1 to September 22, except for hanging lake surveys which were done
between July 21 to 26 in 2006 (Table 1). Each lake was surveyed only once.
Fish Sampling
We used a 4.3 m inflatable boat (the Little Echo) with a 2x2 m mid-water trawl for lakes
that could only be accessed by plane. Meziadin and Morice lakes had road access and were
surveyed with a 7.3 m aluminum power boat (the Night Echo) with a 3x7 m closing trawl (Hume
and MacLellan 2008, MacLellan and Hume 2010). Trawling was our primary method of
sampling the pelagic fish populations, but we collected additional fish samples with Swedish
style gill nets, which were 1.5 m deep and consisted of four, 4 m long panels, with stretched
mesh sizes of 12.5, 16, 20, and 25 mm (Appleberg 2000, MacLellan and Hume 2010). On a
couple of surveys we tried using regular small mesh gill nets as well (19 and 25 mm stretch
mesh, 7.5 x 2.0 m panels), but discontinued their use as they were ineffective. On the hanging
lake surveys we used additional gears including RIC gill nets (seven, 7.5 x 2.0 m panels,
consisting of 19, 64, 38, 89, 51, 76 and 25 mm stretch mesh), minnow traps, beach seines and dip
nets to evaluate fish populations in the littoral zone of the lake. Small fish were preserved in 1
liter plastic sample bottles using 10% formalin or 85% ethanol and processed later at Cultus
Lake Laboratory. Fish too large for our sample bottles were measured for fork length and
released.
Hydroacoustic Sampling
Hydroacoustic sampling was done similarly to Hume and MacLellan (2008). We used a
Biosonics (www.biosonicsinc.com) DTX split beam sounder, transmitting at 208 kHz with a 6.6
degree circular beam. As in our earlier surveys we used a 0.4 ms pulse width, but our collection
threshold decreased over the 4 years covered by this paper. In 2006, we collected at -70 dB; in
2007 we decreased this to -75 dB to aid in detecting smaller organisms such as Chaoborus larva,
and in 2008 we began collecting at -100 dB when improvements to our collection software
allowed us to collect data at a lower threshold (-100 dB) but view it at a higher threshold (-75
dB).
Bathymetric charts are required for several aspects of a hydroacoustic assessment and we
obtained existing charts for eight of our study lakes from the British Columbia Ministry of
Environment, Fisheries Data Warehouse (http://a100.gov.bc.ca/pub/fidq/main.do). However,
two of these charts (Figs. 3a and 3c), Alastair and Bowser Lakes, did not agree well with the
survey soundings, so we created new charts for these lakes based on the transect and other
soundings we took during the survey. Coverage for these two charts were not as complete as
normally obtained, but represented the observed bathymetry of these lakes better than the
existing charts. No existing charts were available for the 12 remaining study lakes, and we
3
compiled new charts using the same techniques and software described in MacLellan and Hume
(2010). Besides depth data from the survey transects, we used data from transects between
survey transects as well as additional sounding in shoal areas and from transects running the long
axis of the lake (when time permitted), to construct these charts (Figs. 3b, 3d to 3n).
Zooplankton Sampling
We used replicated vertical Wisconsin hauls to sample the zooplankton in the pelagic
zone of our study lakes as described in Shortreed et al. 2007). The Wisconsin net had a mouth
opening of 0.05 m2, a mesh size of 160 μm, used a flow meter mounted on the second ring to
measure net efficiency, and was hauled from a depth of 30 m where lake depth permitted.
Samples were preserved in 125 ml plastic bottles using a sucrose buffered 4% formalin solution.
These samples were collected one of two ways, either by our hydroacoustic crew at the time of
our survey, or by our limnology crew as part of a more extensive limnology survey of the lake.
In the latter case, zooplankton sample dates do not correspond exactly with our hydroacoustic
surveys but are usually within a month of one another, except for Keecha, Kooryet, and Moore
Lakes, where the limnology and hydroacoustic surveys were 4 years apart.
Some of the study lakes have Chaoborus populations inhabiting the pelagic zone and the
Wisconsin net does not adequately sample these populations for various reasons (Shortreed et al.
2007). To sample Chaoborus and other macro-invertebrates we used a 350 μm mesh SCORtype net. This net had a 0.25 m2 opening and typically was fished in the same manner as the
Wisconsin net, except sampling was done at night. Samples were preserved in the same manner
as zooplankton.
SAMPLE AND DATA PROCESSING
Hydroacoustic Methods
In this study, we used Myriax’s Echoview software (www.echoview.com) to process
hydroacoustic data. We used four techniques in analyzing the data, echo integration (NTG),
single target analysis (ST), track target analysis (TT) and a variation on tracked target analysis
we call Chaoborus tracked target analysis (Cha-TT) (MacLellan and Hume 2010). A modified
tracked target analysis (Cha-TT) is needed when Chaoborus larva are present in the water
column in significant numbers, as they reflect sound energy similarly to juvenile sockeye and
will inflate the sockeye estimate unless removed from the acoustic data. Each of these methods
is described in Hume and MacLellan (2008) and MacLellan and Hume (2010), and were used to
process the data collected from the study lakes. As in MacLellan and Hume (2010) we usually
report integration results for fish densities >500/ha, TT results where survey densities are
<500/ha and Cha-TT results when Chaoborus is present in significant numbers.
4
Fish and Diet Samples
Fish and diet samples were processed as described in Hume and MacLellan (2008) and
MacLellan and Hume (2010). Large fish were measured for fork length in the field and released.
Smaller fish were preserved in 10% formalin or 85% ethanol and transported back to the lab for
processing. After at least 30 days of preservation, fish were measured for fork length (mm),
weighed (g), and where possible, scales were taken from O. nerka for age determination.
Stomach samples were taken from selected groups (species, size classes, location in lake)
of fish, usually from trawl captured fish that were caught within 3-4 hrs after dusk (normal O.
nerka feeding time). Up to ten fish stomachs were combined in a sample vial, containing a
solution of 10% formalin, for diet analysis. Where possible a replicate sample of up to ten fish
was taken for each group. During analysis, each individual stomach was assessed for fullness
and its contents combined with that of the other stomachs from the vial. These stomach contents
were then sub-sampled as necessary, identified, counted, and where possible, measured, using a
computerized video measuring system as described in MacLellan et al. (1993). With these data,
mean numbers of food items per stomach were calculated and biomass was estimated using
length-weight regressions. See MacLellan and Hume (2010) for details.
Insects comprised a portion of the diet in a number of lakes in this report, but due to their
state of digestion, assessing abundance and biomass of terrestrial insects in the diet was difficult,
resulting in imprecise estimates (MacLellan and Hume 2010). Nevertheless, these numbers do
indicate the presence or absence of insects, and given their individual size relative to most
freshwater zooplankton, it takes few insects to make a significant contribution to the biomass of
a juvenile sockeye’s diet.
Zooplankton Samples
Zooplankton and macro-invertebrate samples were processed using a computerized
video measuring system (Shortreed et al. 2007, MacLellan et al. 1993). Samples were subsampled as necessary and individual zooplankton were identified, counted and measured.
Biomass was estimated using taxa-specific length-weight regressions (MacLellan and Hume
2010).
RESULTS AND DISCUSSION
In this section we discuss the limitations and biases of the sampling gear, and provide an
overall analysis of the catch in relationship to water clarity. Specific results of the survey of each
study lake including methodology, difficulties encountered, and a description of the pelagic fish
communities are presented in Appendix 1. We also evaluate each lake’s suitability for
hydroacoustic assessment and recommend strategies for any future surveys on these lakes. We
also present details of the sampling performed (tow log, Appendix 2), population estimates using
5
the four different analytical techniques (Appendix 3), catch and size data for each gear type
(Appendix 4), and detailed results of the diet analysis (Appendix 5).
LAKE CLASSIFICATION
Hume and MacLellan (2008) classified lakes into three categories (clear, stained and
glacial), and reported results with respect to these groups. The glacial group included any lake
that was subject to glacial melt waters and displayed the typical coloration caused by fine
suspended glacial sediment. For this paper, we revised the approach to glacial lakes. We
observed that many glacial influenced lakes had relatively deep euphotic zones and juvenile
sockeye behavior (diel vertical distribution and diet) was similar to that found in clear lakes. It
seemed reasonable that the degree to which these lakes were affected by glacial melt waters was
important in determining the extent of the effect on lake productivity and sockeye behaviour.
Lloyd et al. (1987) found that compensation depth (depth to which 1% of ambient surface light
penetrates) decreased rapidly above turbidities of 5 NTUs. They also found that reduced light
penetration in the water column led to reduced zooplankton density and that glacial turbid lakes
in Alaska, lacked Cladocera, in particular Daphnia, a favoured food of juvenile sockeye (Lloyd
et al. 1987). We therefore restricted the glacial lakes category to those lakes with turbidity
readings >5 NTUs, and re-labeled it as “glacially turbid” (Table 1). Less glacially influenced
lakes became part of the “clear” lakes group. We did not have turbidity readings for a few study
lakes but did know the compensation depth. We estimated turbidity for these lakes using a linear
regression developed from the other lakes that had both turbidity and light compensation depth
data. Stained lakes were visually classified by field crews observing water colour at the time of
sampling. More quantitative methods for measuring the degree of staining would provide a more
robust categorization. Using the revised classification scheme, only Bowser Lake was classified
as glacially turbid, 9 lakes were classified as clear (6 had some glacial influence) and 10 lakes
were classified as stained (Table 1).
BIASES IN SAMPLING EQUIPMENT
The selectivity of the trawls and gillnets used in these surveys is discussed in MacLellan
and Hume (2010), and as is the case for all sampling equipment, the sampling gear is size
selective (Simmonds et al. 1992). MacLellan and Hume (2010) conclude from a review of the
literature and their own studies that there is little difference in trawl efficiency (catch /m³) or size
bias between the two trawls sizes used (2x2 m and 3x7 m) when sampling age-1 and smaller
sized fish, but that both provide size estimates that are smaller than that of the true population.
The amount of the bias was quite variable amongst the reported studies.
The small mesh gillnets were selected to specifically sample smaller fish (age-0 and -1 O.
nerka and other similar sized fish) and were utilized to supplement and to expose any bias in the
6
small trawl catch. While the size range of O. nerka caught by gill nets tends to overlap with that
of the 2x2 m trawl, the gill nets will catch fish considerably larger than the 2x2 m trawl and were
useful in determining the presence of older age classes of O. nerka and of larger competitors and
predators (Fig. 4a).
For the lake surveys covered by this report, a comparison of September caught O. nerka
by the two trawls indicates that both gears performed equally well for fish up to 75 mm in length.
The large trawl, however was more successful capturing larger O. nerka, in the 75-110 mm
range, than was the small trawl (Fig. 4b). Although most of the large trawl catch (99%) comes
from the Meziadin Lake survey and no gill nets were used on Meziadin, it does demonstrate the
large trawl’s ability to catch this larger size class when they are present in the pelagic fish
population. The small trawl on the other hand, appears to steadily decline in its ability to catch
fish larger than 75mm in length, despite indications from the gill net catch that O. nerka in this
larger size class were encountered (Fig. 4a). Results from this and previous studies suggest that
there is size bias in the trawl data, but it is variable. (MacLellan and Hume 2010, Hyatt et al.
(2004) and McQueen et al. (2007). This is likely because more factors affect trawl net efficiency
than just fish size, such as trawl depth, water clarity, and light conditions.
FISH SPECIES COMPOSITION AND SIZE
Pelagic Fish Composition - Trawl and Gill Net Samples
Trawling was the most effective fish sampling technique. A total of 2 182 minutes of
trawling in 109 trawls with the 2x2 m net caught 2 266 fish for a catch rate of 62 fish/hr, while
155 minutes of trawling in nine trawls with the larger 3x7 m trawl caught 1 065 fish, for a catch
rate of 412 fish/hr (Table 2). Most trawls targeted depths where fish were seen on the echo
sounder, while a few targeted the surface layers, an area of the lake not sampled by the echo
sounder, to check for surface oriented fish populations. Trawls caught mainly O. nerka and
stickleback in clear and stained lakes, while only O. nerka were caught in glacially turbid
Bowser Lake (Table 3, 4). Other trawl caught species included sculpin (Cottus sp), coho salmon
(O. kisutch) and Dolly Varden (Salvelinus malma) (Table 4). Clear and stained lakes produced
age-0 O. nerka of similar size (57-58 mm), while clear lakes produced larger age-1 O. nerka than
those in stained lakes. The glacially turbid lake had the smallest age-0 and age-1 O. nerka at
52mm and 70mm. Stained lakes produced larger stickleback and sculpin than did clear lakes.
(Table 5)
From 2006 to 2009 we set small mesh Swedish gill nets overnight on 94 occasions for a
total of 1 813 hours of fishing time, catching 305 fish. This is an over all catch rate of 3.2
fish/set or an average of 16.9 fish/survey (Table 2). While the general catch of the Swedish gill
nets was lower than the trawls, it’s clear from CPUE data that they performed poorest in stained
lakes, with a CPUE rating an order of magnitude lower than that experienced in either clear or
glacially turbid lakes (Table 2). This, despite the fact that the 2x2 m trawl had the highest CPUE
7
in stained lakes than in either of the other water types (Table 2). These gill nets were only 1.5 m
deep and for the most part we set them over as deep water as practical to sample the pelagic
region of the lake and submerged them to a depth near the thermocline. The Swedish gill nets
caught fewer fish than did the trawls but caught a wider variety of species (Table 2). In all lake
types, the Swedish gill nets caught O. nerka and stickleback that were larger than those captured
with the trawl (Table 5). Again, clear and stained lakes produced similar sized age-0 O. nerka,
with the glacially turbid lake producing smaller age-0 O. nerka and stained lakes had larger
stickleback than did clear lakes (Table 5). Gill nets were not used for the Meziadin or Morice
Lake surveys where the large 3x7 m trawl was employed.
In summary, trawl and Swedish gill net data indicated that clear and stained lakes
produced similar sized O. nerka, while glacially turbid lakes produced somewhat smaller fish. It
also showed that stickleback tended to be larger in stained lakes than in clear lakes and they
appeared to be absent from the glacially turbid lakes in our study.
Hanging Lakes – Fish Composition
On Batchellor, Red Bluff, and Whalen lakes regular (RIC) gill nets, minnow traps, dip
nets and beach scenes were employed close to shore in the littoral zone to sample the near shore
fish community. The 2x2 m trawl and Swedish gill nets were mainly used to assess the pelagic
zone. All three of these lakes were stained and had outlet barriers to anadromous fish migration.
Therefore, any O. nerka must be kokanee. It was not surprising that O. nerka numbers were low
in these lakes, but what was unusual was the absence of stickleback in Batchellor and Whalen
lakes. Other stained lakes in this study support significant populations of stickleback in the
pelagic zone, whereas these two lakes had no detectable sticklebacks (Table 4). No pelagic
stickleback were caught in Red Bluff Lake either, but a few specimens where caught in the
littoral zone.
Sampling the pelagic zone of Batchellor Lake with 45 minutes of trawling and four
overnight gill net sets, produced only one Dolly Varden, caught in a Swedish gill net. Littoral
gear was fished on 11 occasions; two RIC gill nets were set overnight, five minnow traps set
overnight and four beach seines completed. The RIC gillnets caught three Dolly Varden and 56
cutthroat trout, minnow traps caught five Dolly Varden and beach seines captured three Dolly
Varden and 19 cutthroat trout. No kokanee were caught in Batchellor Lake (Table 3). In spite of
the wide variety of gear deployed, only cutthroat trout and Dolly Varden were captured, both
predators on smaller fish. The question arises; what were they feeding on, juvenile cutthroat and
Dolly Varden, or is there some population of forage fish that was not detected by the sampling
gear.
On Red Bluff Lake, seven trawls totaling 138 minutes of fishing time, and three
overnight Swedish gill net sets were completed in the pelagic zone. Trawls caught 17 kokanee,
16 of which were age-0 with an average length of 38 mm (Table 3). Swedish gill nets caught
seven older kokanee but no age-0s; likely due to the small size of these first year fish and the gill
nets not being able to retain them (Table 3). Trawls also caught ten small (10 mm) larval fish
8
and Swedish gill nets also caught three cutthroat trout. In the littoral zone, five RIC gill nets, 11
minnow traps, one dip net, and one beach seine were deployed. The RIC gill nets caught 26
cutthroat trout. Minnow traps caught 122 stickleback along with a few sculpin and cutthroats.
The beach seine caught 28 stickleback and six sculpin and the dip net a single sculpin Appendix
2). With three age classes of O. nerka detected, there is a viable population of kokanee present
in Red Bluff Lake. They, along with stickleback and sculpin, provide a food base for the
cutthroat population.
To sample Whalen Lake’s pelagic zone, four trawls, for 100 minutes of total fishing time,
were conducted, along with four Swedish gill net sets. Each gear caught one age-1 kokanee. In
the limnetic region of the lake, four RIC gill nets and eight minnow traps were deployed. The
RIC gill nets caught 19 Dolly Varden, one coho salmon and eight age-1 kokanee. Minnow traps
caught nine Dolly Varden (Table 6). One Swedish gill net was also deployed near shore to try
and catch on-shore juvenile kokanee, but it came up empty. In short, a small kokanee population
was detected along with a predator population, consisting of Dolly Varden.
HYDROACOUSTIC ABUNDANCE ESTIMATES
The phantom midge larva, Chaoborus, was detected only in stained lakes during this
study. Of the ten stained lakes, Chaoborus were not found in Keecha and Red Bluff lakes and
although detected in Moore Lake, they were not present in sufficient quantities to significantly
hamper regular hydroacoustic assessment and analysis. For the remaining seven stained lakes
Chaoborus densities were high enough to significantly affect acoustic analysis, and Cha-TT
techniques were used to collect and analyze the hydroacoustic data (MacLellan and Hume 2010,
Appendix 3).
After excluding the hanging lakes because of their lack of access for anadromous fish, the
mean O. nerka densities were similar for clear and stained lakes, 564 fish/ha and 517 fish/ha
respectively, ranging from 23 fish/ha in Kwinageese Lake to 2 613 fish/ha in Meziadin Lake
(Table 7). Densities of all small fish in clear (1 291 fish/ha) and stained (1 066 fish/ha) lakes
were also similar on average. The one glacially turbid lake in the study had a much lower small
fish mean density of 39 fish/ha, all O. nerka (Table 7). In stained lakes stickleback dominated
the other small fish component, while in most clear lakes a variety of species made up this
component. The one exception is Alastair Lake, a clear lake with exceptionally high stickleback
densities. If Alastair data were removed from consideration, mean density for clear lake’s other
small fish, would drop from 727 fish/ha to 88 fish/ha.
9
DIET
Diet data from this study and from Hume and MacLellan (2008) were pooled for diet
analysis using the new water clarity classification scheme presented in this paper. The preferred
juvenile O. nerka diet consists mainly of zooplankton, and in particular the cladoceran, Daphnia,
when it is available (Foerster 1968, Hume et al. 1996). Results from this study confirm that
zooplankton is the dominant prey type for clear and stained lakes (Fig. 5). Daphnia predominate
in the juvenile O. nerka diet in clear lakes while Bosmina and Calanoid copepods predominate in
stained lakes (Fig. 6). In glacially turbid lakes, where all Cladocera are largely absent (Lloyd et
al, 1987), O. nerka diets consisted mainly of Calanoid and Cyclopoid copepods, supplemented
with a few terrestrial insects (Figs. 5, 6, 7, 8).
Comparison of the average abundance and biomass of zooplankton, terrestrial insects and
macro-invertebrates in the diet for each of the three water types (Fig. 5), shows that while the
number of zooplankton consumed in clear and stained lakes is similar, the biomass consumed in
stained lakes is roughly 50% that of clear lakes. This reflects the large body size of Daphnia,
which often dominates sockeye diet in clear water lakes. Consumption of zooplankton in
glacially turbid lakes, both in numbers and biomass, is well below that of clear and stained lakes.
Terrestrial insects consumed are relatively few in number, however, because of the greater size
of the insects relative to zooplankton, they contribute greatly to the biomass consumed (Fig. 5).
Insects were the predominant prey type in glacially turbid lakes. Estimates of insect biomass are
inaccurate and probably low, and thus most likely underestimate the importance of terrestrial
insects in the diet of sockeye in glacially turbid lakes (Hume and MacLellan 2008).
Macro-invertebrates consumed by juvenile sockeye included Chaoborus larvae,
Chironomid larvae, Ceratopogonid larvae, Neomysis, worms and amphipods. Individually, these
organisms would contribute greatly to the biomass consumed by a fish due to their large size.
However, they were found only in a few fish from a few of the study lakes and their overall
contribution to sockeye diet is fairly small (Fig. 5).
Threespine stickleback were clearly the most common competitors for food with juvenile
sockeye in the pelagic zone of the study lakes, particularly in the stained lakes. This is partly
because many of the study lakes are on or near the coast where the lakes tend to be stained and
threespine stickleback are a coastal species, rarely found far inland (McPhail, 2007). Stickleback
were captured by midwater trawl in sufficient numbers to analyze diet data in 12 out of 19
stained lakes, while only one clear lake (Alastair) produced significant numbers of stickleback
(Appendix 2, Table 4). Stickleback diet in stained lakes was similar to that of juvenile sockeye
(Figs. 6 and 9). In clear Alistair Lake, stickleback also ate the same zooplankton as sockeye,
Bosmina and cyclopoids (Appendix 5).
Other possible competitor species include whitefish (Coregonus spp.), lake chub
(Couesius plumbeus), and redside shiners (Richardsonius balteatus) (McPhail, 2007). Although
we did not often encounter these species in significant numbers in the midwater pelagic zones of
the study lakes, these species are known to prey on a large variety of organisms and the potential
10
for food competition with juvenile sockeye exists (Hume and MacLellan 2008). Lake chub diet
consisted of Bosmina and insects, while redside shiners and whitefish primarily consumed
insects and macro-invertebrates (Appendix 5).
PLANKTIVORE BIOMASS AND PREDICTED PRODUCTION
DFO’s policy for the conservation of wild salmon (DFO 2005) requires the monitoring
and assessment of the status of sockeye stocks or conservation units (CUs). One useful tool for
determining the current status of a particular sockeye stock CU is to compare the observed
biomass of the age-0 juvenile sockeye population from these pelagic surveys with the predicted
lake capacity from models of rearing capacity, such as the photosynthetic rate (PR) model
(Hume et al. 1996, Shortreed et al. 2000, Cox-Rogers et al. 2004, Hume and MacLellan 2008).
The PR model predicts total planktivorous fish biomass but these predictions must be revised
downwards if other planktivorous fish species other than age-0 sockeye are present in the pelagic
zone and are and competing for the same prey items (Cox-Rogers et al. 2004). We found that
potential competitors for the zooplankton resources in these lakes include the pelagic forms of
threespine stickleback, whitefish, Dolly Varden, sculpin, coho, and cutthroat trout. Using
estimates of abundance and size from the hydroacoustic estimates and the trawl catch, we used
these species in the calculation of both juvenile sockeye and potential competitor biomass as
required for the model (Table 7).
Biomass of juvenile sockeye and their fish competitors was determined from the
hydroacoustic estimates and the mean size of the fish in the trawl catch. If trawl catch data was
inadequate, then information from gillnets was used (Table 7). In clear lakes, juvenile sockeye
and competitor biomass averaged 1.7 kg/ha and 1.2 kg/ha respectively. In stained lakes, age-0
sockeye and competitor biomass averaged 1.2 kg/ha and 1.0 kg/ha respectively. In both lake
types age-0 sockeye averaged 54 - 58% of the total planktivore biomass. In the one glacially
turbid lake in this report, Bowser Lake, age-0 biomass was only 0.1 kg/ha and there were no
pelagic competitors. It is worth noting however, that the competitor biomass in clear lakes is
largely driven by the large stickleback population in Alastair Lake. If we remove Alastair from
the analysis, competitor biomass for clear lakes drops two orders of magnitude to .027 kg/ha,
while sockeye biomass remains much the same at 1.6 kg/ha, and juvenile sockeye biomass now
makes up 98% of total planktivore biomass in clear lakes. This suggests clear lake juvenile
sockeye, rearing outside the geographic range of threespine stickleback, which is mostly within
200 km of the coast (McPhail 2007), have very little competition for food resources in the
pelagic zone of these lakes. In contrast, sockeye populations that share either stained or clear
lakes with threespine stickleback (coastal and near coastal lakes) experience significant
competition for food resources. This must be considered when estimating carrying capacity.
Hall et al. (In press) used the estimated biomass results to determine the status of the sockeye
CUs of the Nass River watershed.
11
WATER CLARITY SUMMARY
Although there were some inconsistencies, our surveys of 43 lakes in northern British
Columbia, this study and Hume and MacLellan (2008), found distinct differences between lake
types in species composition, and in juvenile sockeye vertical distribution and diet.
Juvenile sockeye and threespine stickleback were generally the dominant fish species in
the pelagic area of the 24 clear and 16 stained lakes (Appendix 2, Hume and MacLellan 2008).
Similarly to the lakes in our studies, threespine stickleback were the most common competitor
species found in other BC lakes (O’Neill and Hyatt 1987). Other species, such as sculpins, lake
chub, redside shiner, and whitefish (Appendix 2), were sometimes captured as well. Unlike the
three glacially turbid lakes we surveyed in this study and in Hume and MacLellan (2008), where
juvenile sockeye were the only trawl caught fish, Chernoff (1971) found abundant threespine
stickleback populations in Owikeno Lake. This difference may be related to the coastal location
of Owikeno Lake compared to the inland locations of the other lakes.
Diel vertical migration is well known in juvenile sockeye salmon and is thought to be an
adaptation to avoid predation by fish predators (Clarke and Levy 1988, Scheuerell and Schindler
2003). Juvenile sockeye typically spend the day at depths where light conditions preclude visual
predation, rise to feed in the epilimnion at dusk and dawn, and spend the night in the upper
hypolimnion, generally near the thermocline. In clear lakes, daytime O. nerka depths are
typically >40 m (Narver 1970, Levy 1990) but can be much shallower in stained and glacially
turbid lakes (Chernoff 1971, data on file). In the clear and stained lakes of our studies, sockeye
were generally found well below the surface at night (typically 10-30 m deep), usually in the
upper hypolimnion, but sockeye in two of the glacially turbid lakes, Motase and Bowser, were
found in near surface waters at night and were mostly found near shore in Bowser Lake (data on
file, Hume and MacLellan 2008). The third glacially turbid lake, Kitsumkalum, had a turbidity
reading (5.5 NTUs) only slightly above our classification threshold for turbid lakes and night
time vertical distribution was similar to that seen in clear lakes, with juvenile sockeye found
below the thermocline at 10-30 m (Hume and MacLellan 2008).
When available, cladocerans, particularly Daphnia, are the preferred prey for juvenile
sockeye in many lakes. Daphnia is usually abundant and often the dominant macrozooplankter in
the clear lakes of these studies (Shortreed et al. 2007). Average Daphnia biomass was lower in
stained lakes and Bosmina was often the most abundant cladoceran. Cladocerans were either
absent or very sparse in glacially turbid lakes and the plankton communities in these lakes were
usually dominated by the copepod Diacyclops. These differences in the macrozooplankton
community were reflected in the juvenile sockeye diet where cladocerans were the major dietary
item in clear and stained lakes, with Daphnia the major food item in clear lakes and the smaller
Bosmina in stained lakes (Figs. 8 and 9). As expected, there were no cladocerans in the diet of
juvenile sockeye in glacially turbid lakes and copepods were the most abundant prey item.
12
However, terrestrial insects were also relatively abundant in the diet and probably provided the
most biomass to juvenile sockeye diet in glacially turbid lakes.
ACKNOWLEDGEMENTS
Brock Stables (Shuksan Fisheries Consulting, PO Box 485, Sumas, WA 98295), provided
much useful advice over the course of this study. Steve McDonald conducted most of the field
work with assistance from Jeff Amos, Rodney Harris, and Adam Chateauvert. Shirley Fuchs did
most of the in laboratory fish processing and Mary-Jane Hudson analyzed the stomach contents.
The fish were aged by the staff of the scale lab at the Pacific Biological Station under the
direction of Shayne MacLellan. Peter Hall and Lucas Pon provided valuable reviews of earlier
drafts.
This project was partially supported by funding from the Pacific Salmon Treaty through
the Stock Assessment Division, North Coast Area, of DFO and by DFO funding as part of the
implementation of Canada's 2005 Policy for the Conservation of Wild Salmon.
13
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16
Table 1. Location and morphological data for each of the study lakes. The number of trawling sections and acoustic transects are
shown.
Lake
17
Alastair
Batchellor
Bowser
Elbow
Fred Wright
Keecha
Kimsquit
Kitlope
Koeye
Region
Water type
Recorded
Turbidities
(NTU)a
Date
surveyed
Lat.
(ºN)
Long.
(ºW)
Elevation
(m)
Coastal Skeena
North coast
Interior Nass
Interior Bella Coola
Interior Nass
North coast
North coast
North coast
Central coast
North coast
Interior Nass
Interior Bella Coola
Interior Nass
North coast
Interior Skeena
Central coast
North coast
Central coast
Central coast
North coast
Clear
Stained
Glacially turbid
Clearb
Clear
Stained
Clearb
Clearb
Stained
Stained
Clear
Clearb
Clearb
Stained
Clearb
Stained
Stained
Stained
Stained
Stained
1.1
0 - 1.3
18.2 - 59.6
1.5 - 4.8
0.3 - 0.9
0.1
0.1
1.3
0.01
0.4
0.3 - 0.9
0 - 0.9
0.77 - 3.4
0.2
3.7
0.35
0 - 0.14
0.57
0.7
-
13-Sep-09
20-Jul-06
04-Sep-09
19-Sep-07
09-Sep-09
04-Sep-08
12-Sep-07
15-Sep-07
12-Sep-06
01-Sep-08
07-Sep-09
08-Sep-07
17-Sep-09
07-Sep-08
22-Sep-09
15-Sep-06
23-Jul-06
18-Sep-06
19-Sep-06
26-Jul-06
54º11'
53º36'
56º27'
52º05'
55º58'
53º18'
53º07'
53º06'
51º46'
53º21'
56º03'
52º14'
56º04'
53º25'
54º00'
51º52'
53º28'
52º19'
52º21'
53º13'
129º19'
129º40'
129º34'
125º42'
128º45'
129º54'
127º24'
127º47'
127º42'
129º59'
128º49'
125º43'
129º18'
129º31'
127º37'
127º50'
129º36'
128º16'
128º16'
128º56'
45
88
368
580
597
13
358
13
53
21
631
483
246
5
763
9
36
7
11
120
Kooryet
Kwinageese
Lonesome
Meziadin
Moore
Morice
Namu
Red Bluff
Tankeeah (lower)
Tankeeah (upper)
Whalen
a
Data on file
b
Glacially influenced, but generally not turbid (NTU<5)
c
Bathymetry for Morice is very poor, depths are rough estimates only
Surface
area
(ha)
Mean
depth
(m)
Max.
depth
(m)
# of
sections
# of
transects
686
567
3409
138
386
332
166
1170
450
509
259
410
3599
280
9738
317
795
152
129
2131
21
66
65
13
18
16
35
51
41
19
18
12
42
22
92+c
21
65
8
10
100
79
131
116
34
42
65
75
123
63
63
64
41
134
67
154+c
58
199
29
32
255
2
1
2
1
1
4
1
1
2
3
1
1
2
2
3
2
3
3
2
2
8
7
12
7
9
12
7
7
7
10
8
7
10
11
10
8
8
10
7
13
Table 2. Fish caught by midwater trawls and gill nets in lakes of different water types. CPUE was determined by dividing total
catch of each taxa by total trawling time in each water type. CPUE for gill nets was based on over night sets.
Taxa
Clear
2x2m Trawl
3x7m Trawl
Swedish gill nets
Mean CPUE (catch/hr)
Mean CPUE (catch/hr)
Mean CPUE (catch/set)
Glacially
turbid
Stained
Mean
Clear
Clear
Glacially
turbid
Stained
Mean
O. nerka
Age-0
Age-1
Age-2+
Adult / jack
Threespine stickleback
18
Sculpin
Sucker
Lake chub
Northern pikeminnow
Redside shiner
Whitefish
Coho salmon
Bull trout
Dolly Varden
Cutthroat trout
Rainbow trout
All fish
# of species captured
N (number of lakes)
15.2
3.8
5.1
4.3
0.6
49.4
0.6
279.1
132.4
0.9
0.9
0.3
0.1
36.7
0.1
58.1
0.8
0.6
5.2
1.8
0.2
0.1
0.2
0.7
0.1
0.1
0.1
1.7
0.8
0.3
0.1
0.0
0.4
0.3
0.0
0.1
0.0
0.1
78.2
4
7
9.9
1
1
87.1
4
10
62.0
5
18
412.3
2
2
4.3
9
7
8.5
4
1
0.8
3
10
3.2
10
18
Table 3. Catch and size of O. nerka caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed Swedish nets,
except where indicated.
Lake
Alastair
19
Bowser
Elbow
Trawl caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
Gill net caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
Clarity
O. Nerka
age group
Clear
Age 0
Formalin
Ethanol 85%
34
13
47
1.74
1.78
0.18
0.18
54
59
55
2.2
1.8
1
2.17
Age 1
Formalin
Ethanol 85%
42
7
49
4.76
4.71
0.31
0.32
76
79
76
1.6
1.4
2
6
9.02
80
38.1
Age 0
Formalin
Ethanol 85%
12
13
25
1.87
1.36
0.55
0.32
53
52
52
5.5
4.4
6
2.2
0.22
58
3.4
Age 1
Formalin
Ethanol 85%
14
7
21
4.36
3.02
0.41
1.19
71
68
70
2.2
9.8
62
4.69
0.29
74
1.4
Age 2+
Formalin
Ethanol 85%
1
2
3
11.05
6.02
95
85
88
21
11.14
2.19
96
5.6
9.21
25.4
11
5.66
1.65
80
6.3
3
4
7
9.22
7.34
3.95
5.94
88
86
87
13.1
22.1
1
26.15
Glacially turbid
Clearg
Age 0
Age 1
Preservative
Formalin
Ethanol 85%
Ethanol 85%
N
N
58
134
Table 3. Catch and size of O. nerka caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed Swedish nets,
except where indicated (Continued).
Lake
Fred Wright
20
Keecha
Kimsquit
Kitlope
Clarity
Clear
Stained
Clearg
Clearg
O. Nerka
age group
Preservative
Age 2+
Formalin
Ethanol 85%
Age 0
Formalin
Age 1
Formalin
Age 0
Formalin
Ethanol 85%
Age 1
Formalin
Age 0
Formalin
Ethanol 85%
Age 1
Formalin
Age 0
Formalin
Ethanol 85%
Age 1
Formalin
N
2
Trawl caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
3.51
11.75
65
63.5
172
20
192
1.96
1.89
0.11
0.25
55
59
55
1
2.3
4
5.62
1.67
79
7.2
13
20
33
1.33
1.19
0.55
0.42
45
48
47
6.4
6.1
N
Gill net caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
3
2
5
95.93
82.81
37.83
146.82
192
198
194
26.6
38.1
2
7.06
10.42
84
50.8
4
14.99
17.04
106
32.7
8
4.09
0.77
69
4.8
8
6.96
2.05
82
7.6
75
25
100
1.38
1.1
0.11
0.13
49
51
50
1.3
1.9
6
2.42
0.55
59
3.7
5
4.6
1.13
73
7.9
17
5.04
0.57
76
2.9
Table 3. Catch and size of O. nerka caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed Swedish nets,
except where indicated (Continued).
Lake
Clarity
O. Nerka
age group
Preservative
Ethanol 85%
Age 2+
Formalin
N
5
10
Trawl caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
3.44
0.88
70
72
5.8
21
Koeye
Stained
Age 0
Formalin
Ethanol 85%
36
34
70
1.79
1.44
0.23
0.13
52
55
53
2.7
1.7
Kooryet
Stained
Age 0
Formalin
Ethanol 85%
35
26
61
2.34
1.91
0.41
0.26
57
59
58
2.9
2.5
Age 1
Ethanol 85%
1
2.54
67
Age 0
Formalin
1
0.72
38
Age 1
Formalin
1
14.11
101
Age 2+
Formalin
Age 0
Formalin
Ethanol 85%
Age 1
Formalin
Kwinageese
Lonesome
Clear
Clearg
34
29
63
1.89
1.83
0.24
0.42
54
58
56
N
Gill net caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
2.1
3.2
1
14.68
107
1
29.13
130
3
6
9
2.93
3.19
1
25.63
1.76
0.22
62
70
67
127
11.1
2.1
Table 3. Catch and size of O. nerka caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed Swedish nets,
except where indicated (Continued).
Lake
Clarity
O. Nerka
age group
Preservative
Ethanol 85%
Meziadin
Clearg
N
3
Trawl caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
10.04
5.92
101
N
Gill net caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
19.9
22
Age 2+
Formalin
Age 0
Formalin
Ethanol 85%
381
60
441
1.84
1.73
0.09
0.15
54
57
54
0.8
1.7
Age 1
Formalin
Ethanol 85%
99
36
135
9.53
8.69
0.5
0.87
94
96
95
1.5
3.2
Moore
Stained
Age 0
Formalin
Ethanol 85%
62
20
82
2.75
2.32
0.11
0.22
62
63
62
0.9
2.2
Morice
Clearg
Age 0
Formalin
20
4.12
0.94
70
5.5
Age 1
Formalin
2
13.06
7.24
102
38.1
Namu
Stained
Age 0
Formalin
Ethanol 85%
21
20
41
2.12
1.9
0.35
0.44
54
57
55
3.4
4.2
Red Bluff
Stained
Age 0
Ethanol 85%
16
0.4
0.12
38
4
2
203.6
1
2.34
1001.3
238
59
565.4
Table 3. Catch and size of O. nerka caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed Swedish nets,
except where indicated (Continued).
Lake
Clarity
O. Nerka
age group
Preservative
Age 1
Ethanol 85%
Age 2+
Ethanol 85%
N
1
Trawl caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
7
93
23
Tankeeah (lower)
Stained
Age 0
Formalin
Ethanol 85%
10
19
29
2.35
2.64
0.63
0.42
57
65
62
4.6
3.5
Tankeeah (upper)
Stained
Age 0
Ethanol 85%
4
1.94
0.52
60
4.5
Whalen
Stained
Age 1
Ethanol 85%
1
3.41
Age 1a
Ethanol 85%
a
- RIC gill net was used.
g
- glacially influenced, but generally not turbid (NTU<5).
74
N
Gill net caught O. nerka
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
5
11.14
4.59
105
11.6
2
57.62
3.37
173
31.8
1
6.34
80
1
13.25
116
8
9.34
1.37
100
5.6
Table 4. Catch and size of other fish species caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed
Swedish nets, except where indicated.
Lake
Alastair
Batchellor
Clarity
Clear
Stained
Species
Preserv.
Threespine stickleback
Formalin
Live
Cutthroat trout
Livea
Dolly Varden
N
353
Trawl caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
1.45
0.07
50
60
40
56
13.1
56
242
10.0
Live
Livea
1
3
4
222
152
170
59.6
Adult/jack sockeye
Live
2
516
50.8
Bull trout
Formalin
Live
1
3
4
23.49
121
347
291
138.0
Coho salmon
Formalin
5
14.37
103
6.2
Sucker
Formalin
1
24.15
Coho salmon
ethanol
Northern pikeminnow
Formalin
3
139.27
24
Bowser
Elbow
Glacially turbid
Clearg
1
9.92
1.0
N
4
1
5
Gill net caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
2.28
1.27
2.74
120
99
45.81
223
32.3
Table 4. Catch and size of other fish species caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed
Swedish nets, except where indicated (Continued).
Lake
Fred Wright
Keecha
Clarity
Clear
Stained
Species
Preserv.
N
5
Trawl caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
25
Sculpin
Formalin
0.10
Bull trout
Live
Sculpin
Formalin
2
Adult/jack sockeye
Live
1
Dolly Varden
Formalin
1
27.78
140
Prickly sculpin
Formalin
1
1.98
62
Threespine stickleback
Formalin
69
2.25
1
0.33
0.08
Sculpin
ethanol
Kitlope
Clearg
Coho salmon
Formalin
Threespine stickleback
Formalin
2
0.96
1
0.27
44
3.53
Threespine stickleback
ethanol
Kooryet
Stained
Threespine stickleback
Formalin
7.7
0.44
17
555
31.8
380
Clearg
Stained
21
1
Kimsquit
Koeye
0.12
N
Gill net caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
0.22
63
2.1
1
2.02
66
2
4.94
69.9
1
1.14
46
2.5
1
4.07
77
34
4.38
45
16.01
71
31
0.26
73
76.2
Table 4. Catch and size of other fish species caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed
Swedish nets, except where indicated (Continued).
Lake
Kwinageese
Clarity
Clear
Species
Preserv.
N
4
Trawl caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
0.36
0.40
31
Coho salmon
Formalin
10.2
Lake chub
Formalin
5
18.52
Rainbow trout
Formalin
1
27.05
Redside shiner
Formalin
Live
55
1
56
7.15
Cutthroat trout
Live
1
265
Rainbow trout
Live
1
331
Prickly sculpin
Formalin
3
4.25
5.96
66
28.6
Sculpin
Formalin
ethanol
2
1
3
0.31
0.16
1.52
31
27
30
57.2
Whitefish
Formalin
1
22.50
26
Lonesome
Meziadin
Clearg
Clearg
N
Gill net caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
125
7.99
115
19.5
129
0.44
78
80
78
1.5
Table 4. Catch and size of other fish species caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed
Swedish nets, except where indicated (Continued).
Lake
Clarity
Species
Preserv.
N
Trawl caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
27
Moore
Stained
Threespine stickleback
Formalin
ethanol
231
5
236
0.77
1.10
Morice
Clearg
Whitefish
Formalin
1
6.47
Namu
Stained
Threespine stickleback
Formalin
6
4.45
Red Bluff
Stained
Cutthroat trout
Live
Livea
Larval fish
ethanol
Threespine stickleback
Formalin
ethanol
Coho salmon
Formalin
Threespine stickleback
Formalin
Tankeeah (lower)
Tankeeah (upper)
Stained
Stained
0.09
0.79
38
47
38
1.8
19.0
N
20
Gill net caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
1.40
2.19
10
7
76
10
0.37
0.20
1.62
52
1.6
476
352
365
81.8
17.3
89
13.6
3
26
29
1
1
2
0.16
1.0
34
29
32
0.23
55
1.6
1
1.55
51
1
8.64
82
Table 4. Catch and size of other fish species caught in the trawl and gill nets in the surveyed lakes. Gill nets were small meshed
Swedish nets, except where indicated (Continued).
Lake
Whalen
a
g
Clarity
Stained
Species
Preserv.
N
Trawl caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
N
Gill net caught
Weight (g)
Length (mm)
Mean 95%CI Mean 95%CI
Coho salmon
Livea
1
42.11
Dolly Varden
Livea
19
39.40
RIC gillnet used
glacially influenced, but generally not turbid (NTU<5)
141
23.92
189
47.8
28
Table. 5. Mean length of commonly caught pelagic fish species from sockeye rearing lakes
for each water type. Hanging lakes are not included.
Gear
Trawls
Swedish gill nets
Clear
Stained
Glacially
turbid
Clear
Stained
Glacially
turbid
9
7
1
7
7
1
# of lakes
Length (mm)
95% CI (mm)
9
57
8
7
58
3
1
52
-
6
71
10
2
70
21
1
58
-
# of lakes
Length (mm)
95% CI (mm)
6
91
11
3
73
7
1
70
-
6
101
20
1
116
-
1
74
-
# of lakes
Length (mm)
95% CI (mm)
0
0
1
88
-
4
167
59
0
1
96
-
2
48
5
7
53
14
0
2
51
10
4
62
12
0
5
34
17
1
62
-
0
0
0
0
Water type
# of Lakes Surveyed
O. nerka, age-0
O. nerka, age-1
O. nerka, age-2
Threespine stickleback
# of lakes
Length (mm)
95% CI (mm)
Sculpin sp.
# of lakes
Length (mm)
95% CI (mm)
29
Table 6. Size of fish caught with other gears from the surveyed lakes.
Lake
Batchellor
Lonesome
30
Red Bluff
Whalen
Clarity
Stained
Clear
Stained
Stained
Gear
Beach sceine
Species
Preservative
N
Weight (g)
Mean
95%CI
Length (mm)
Mean
95%CI
Cutthroat trout
Formalin
19
3.45
2.3
51
13
Dolly Varden
Formalin
3
6.36
4.76
79
18.8
Minnow trap
Dolly Varden
Live
5
121
28.1
Dip net
Northern pikeminnow
Formalin
1
96.33
193
Prickly sculpin
Formalin
1
41.42
135
Sculpin
Formalin
6
0.23
0.07
28
3.2
Threespine stickleback
Formalin
28
0.71
0.15
41
2.7
Dip net
Sculpin
Formalin
1
1.48
Minnow trap
Sculpin
Formalin
3
1.36
Cutthroat trout
Live
1
350
Sculpin
Live
1
60
Threespine stickleback
Live
122
49
0.8
Dolly Varden
Live
9
111
9.7
Beach sceine
Minnow trap
53
0.5
52
10.3
Table 7. Estimated abundance and biomass of juvenile O. nerka and dominant competitor fish species in the study lakes. Density
estimates from Appendix 3. Size estimates are average weight of formalin preserved juvenile O. nerka (age-0, age-1 and sometimes
age-2) from Appendix 4.
All Small
Lake
Water
clarity
Date
Analysis
method
Reliability
of
estimate
fish
Density
(n/ha)
Juvenile O. nerka
Competitor Species
Density
(n/ha)
Size a
(g)
Biomass
(kg/ha)
Dominant
speciesb
Juvenile O. nerka
Density
(n/ha)
Size a
(g)
Biomass
(kg/ha)
fish
Density
(n/ha)
5836
1.5
8.462
92
9
18
14
0.1
0.001
100
92
100
610
0.1
0.049
7
16
89
Density
(%)
Biomass
(%)
Alastair
Clear
13-Sep-09
NTG
Medium
6380
544
3.4
1.855
Elbow
Clear
20-Sep-07
TT
Medium
167
153
5.7
0.864
Fred Wright
Clear
09-Sep-09
TT
Low
728
118
3.5
0.414
Clear
13-Sep-07
NTG
High
784
761
1.3
1.012
Sculpin
23
-
-
138
97
-
Kitlope
Clear
15-Sep-07
TT +
Trawl
Low
280
275
1.6
0.435
Stickleback,
coho
5
1.0
0.005
9
98
99
Kwinageese
Clear
07-Sep-09
TT
Low
68
23
7.4
0.168
Coho
46
0.4
0.016
14
33
91
Lonesome
Clear
08-Sep-07
NTG
High
496
496
1.9
0.937
0
-
-
24
100
-
Meziadin
Clear
17-Sep-09
NTG
Medium
2616
2613
3.4
8.953
Whitefish
3
22.5
0.063
295
100
99
Morice
Clear
22-Sep-09
TT
Very low
97
93
5.2
0.480
Whitefish
4
6.5
0.027
4
96
95
1291
564
3.7
1.680
727
4.6
1.232
76
44
58
Kimsquit
31
Mean for
clear lakes
Stickleback
Large
Sculpin,
NPM, coho
Possibly
sculpin
Keecha
Stained
04-Sep-08
Cha-TT
Medium
1184
727
2.0
1.485
Stickleback
457
2.6
1.191
34
61
55
Koeye
Stained
12-Sep-06
Cha-TT
Medium
1085
1063
1.8
1.903
Stickleback
22
-
-
58
98
-
Kooryet
Stained
01-Sep-08
NTG
High
781
241
2.3
0.564
Stickleback
(large)
540
3.5
1.907
16
31
23
Table 7. Estimated abundance and biomass of juvenile O. nerka and dominant competitor fish species in the study lakes. Density
estimates from Appendix 3. Size estimates are average weight of formalin preserved juvenile O. nerka (age-0, age-1 and sometimes
age-2) from Appendix 4 (Continued).
All Small
Lake
Water
clarity
Date
Analysis
method
Reliability
of
estimate
fish
Density
(n/ha)
Juvenile O. nerka
Competitor Species
Density
(n/ha)
Size a
(g)
Biomass
(kg/ha)
Dominant
speciesb
Large
Density
(n/ha)
Size a
(g)
Biomass
(kg/ha)
fish
Density
(n/ha)
Juvenile O. nerka
Density
(%)
Biomass
(%)
32
Moore
Stained
07-Sep-08
NTG
Medium
2364
229
2.8
0.631
Stickleback
2134
0.8
1.643
5
10
28
Namu
Stained
15-Sep-06
Cha-TT
Medium
628
548
2.1
1.161
Stickleback
80
4.5
0.357
87
87
76
Stained
18-Sep-06
Cha-TT
Medium
514
479
2.7
1.300
Stickleback
35
0.4
0.013
141
93
99
Stained
19-Sep-06
Cha-TT
Medium
907
330
-
-
Stickleback
577
1.6
0.934
26
36
-
1066
517
1.008
52
48
54
0.000
0
100
100
Tankeeah
(lower )
Tankeeah
(upper)
Mean for
stained lakes
2.3
1.174
549
0
Glacially
turbid
04-Sep-09
TT &
Trawl
Very low
39
39
3.5
0.136
Batchellor
Stained
21-Jul-06
Cha-TT
Medium
150
0
-
-
Red Bluff
Stained
23-Jul-06
TT
High
166
166
-
Whalen
Stained
26-Jul-06
Cha-TT
Medium
74
74
-
Bowser
2.2
Hanging
lakes
a
b
Cutthroat,
Dolly
150
-
-
26
0
-
-
0
-
0.000
46
100
-
-
0
-
-
101
100
-
average weight of formalin preserved fish caught in trawls
NPM (Northern pikeminnow), stickleback (threespine stickleback), cutthroat (cutthroat trout), Dolly (Dolley Varden)
3
13
British
Columbia
11
5
Survey Lakes:
Prince
Rupert
1
15
2
10
17
14
6
20
8
18&19
7
Alastair
Batchellor
Bowser
Elbow
Fred Wright
Keecha
Kimsquit
Kitlope
Koeye
Kooryet
Kwinageese
Lonesome
Meziadin
Moore
Morice
Namu
Red Bluff
Tankeeah (lower)
Tankeeah (upper)
Whalen
Bella Coo la River
N
12
4
16
9
kilometers
0
50
100
Fig. 1. Overview map of study region showing the location of the surveyed lakes.
33
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Tr 8
Tr 7
N
Tr 6
Section 2
1 kilometer
Tr 5
Alastair Lake
Tr 4
Tr 3
Tr 2
Tr 1
Section 1
Fig. 2a. Map of Alastair Lake showing the trawl sections and hydroacoustic transects.
34
.
N
1 kilometer
Tr 1
Batchellor Lake
Tr 2
Tr 3
Tr 4
Section 1
Tr 5
Tr 6
Tr 7
Fig. 2b. Map of Batchellor Lake showing the trawl sections and hydroacoustic transects.
35
Tr 1
Tr 2
Tr 3
Tr 4
Tr 5
Section 1
Tr 6
N
Tr 7
3 kilometers
Tr 8
Bowser Lake
Tr 9
Section 2
Tr 10
Tr 11
Tr 12
Fig. 2c. Map of Bowser Lake showing the trawl sections and hydroacoustic transects.
36
Outlet
Shallows
Tr 1
Tr 2
N
Tr 3
Tr 4
Section 1
1 kilometer
Tr 5
Elbow Lake
Tr 6
Tr 7
Fig. 2d. Map of Elbow Lake showing the trawl sections and hydroacoustic transects.
37
N
Tr 1
1 kilometer
Tr 2
Fred Wright Lake
Tr 3
Tr 4
Tr 5
Section 1
Tr 6
Tr 7
Tr 8
Tr 9
Fig. 2e. Map of Fred Wright Lake showing the trawl sections and hydroacoustic transects.
38
Section 1
Tr 1
Tr 3
Tr 2
Tr 4
Tr 5
N
Section 2
Tr 6
1 kilometer
Keecha Lake
Tr 7
Section 3
Tr 8
Tr 9
Tr 10
Tr 11
Section 4
Tr 12
Fig. 2f. Map of Keecha Lake showing the trawl sections and hydroacoustic transects.
39
Tr 1
Tr 2
Tr 3
Tr 4
Tr 5
Section 1
N
1 kilometer
Tr 6
Kimsquit Lake
Tr 7
Inlet
Shallows
Fig. 2g. Map of Kimsquit Lake showing the trawl sections and hydroacoustic transects.
40
Outlet
Shallows
N
2 kilometer
Tr 1
Kitlope Lake
Tr 2
Tr 3
Section 1
Tr 4
Tr 5
Tr 6
Tr 7
Fig. 2h. Map of Kitlope Lake showing the trawl sections and hydroacoustic transects.
41
N
1 kilometer
Tr 8
Koeye Lake
Tr 7
Section 1
Little Koeye Lake
Tr 6
Tr 2
Tr 3
Tr 4
Tr 5
Fig. 2i. Map of Koeye Lake showing the trawl sections and hydroacoustic transects.
42
Tr 1
Tr 2
Section 1
Tr 3
Tr 6
Tr 4
Section 2
Tr 5
Tr 7
Tr 8
Section 3
N
Tr 9
1 kilometer
Tr 10
Kooryet Lake
Outlet
Shallows
Fig. 2j. Map of Kooryet Lake showing the trawl sections and hydroacoustic transects.
43
Tr 1
N
1 km
Kwinageese Lake
Tr 2
Tr 3
Tr 4
Section 1
Tr 5
Tr 6
Tr 7
Tr 8
Fig. 2k. Map of Kwinageese Lake showing the trawl sections and hydroacoustic transects.
44
Tr 1
Tr 2
Tr 3
Section 1
N
Tr 4
Tr 5
Tr 6
1 kilometer
Lonesome Lake
Tr 7
Southern
Shallows
Fig. 2l. Map of Lonesome Lake showing the trawl sections and hydroacoustic transects.
45
Section 1
Tr 1.0
Tr 1.5
Tr 2.0
Tr 2.5
Tr 3.1
Section 2
Tr 3.7
Tr 4.3
N
N
Tr 4.9
Tr 5.6
2 km
2 km
Tr 6.3
Meziadin
LakeLake
Meziadin
Fig. 2m. Map of Meziadin Lake showing the trawl sections and hydroacoustic transects.
46
Tr 1
Tr 2
N
Tr 3
Tr 4
1 kilometer
Section 1
(fresh water)
Tr 5
Moore Lake
Tr 6
Tr 7
Tr 8
Tr 9
Tr 10
Tr 11
Section 2
(deep saline layer)
Fig. 2n. Map of Moore Lake showing the trawl sections and hydroacoustic transects.
47
Section 1
Atna Bay
Section 3
Atna Arm
Section 2
Fig. 2o. Map of Morice Lake showing the trawl sections and hydroacoustic transects.
48
Tr 8
Tr 7
Section 2
Tr 6
N
1 kilometer
Tr 4
Tr 5
Section 1
Namu Lake
Tr 3
Tr 2
Tr 1
Fig. 2p. Map of Namu Lake showing the trawl sections and hydroacoustic transects.
49
Tr 1
Tr 2
Section 1
Tr 3
Section 2
Tr 4
N
1 kilometer
Tr 5
Red Bluff Lake
Tr 6
Tr 7
Section 3
Tr 8
Fig. 2q. Map of Red Bluff Lake showing the trawl sections and hydroacoustic transects.
50
N
500 meters
Tr 6
Section 2
Tankeeah Lake (lower)
Tr 7
Tr 4
Tr 5
Tr 3
Tr 8
Section 1
Tr 2
Tr 9
Tr 1
Section 3
Tr 10
Fig. 2r. Map of Tankeeah Lake (lower) showing the trawl sections and hydroacoustic transects.
51
Tr 7
N
Tr 6
Section 2
Tr 5
500 meters
Tr 3
Tankeeah Lake (upper)
Tr 4
Tr 2
Section 1
Tr 1
Fig. 2s. Map of Tankeeah Lake (upper) showing the trawl sections and hydroacoustic transects.
52
Tr 1
Section 2
Tr 2
Tr 3
Tr 4
Tr 5
Tr 6
Tr 7
Tr 8
N
Tr 9
2 kilometers
Section 1
Tr 10
Whalen Lake
Tr 11
Tr 12
Tr 13
Fig. 2t. Map of Whalen Lake showing the trawl sections and hydroacoustic transects.
53
Alastair Lake
0m
Alastair Lake
Surveyed for:
Surveyed by:
Drawn by:
Base map:
500 m 1000 m 1500 m 2000 m
54.11 º N 129.18 ° W : Easting 9U 488190 Northing 5995197
Fisheries and Oceans, Canada
Survey Date: September 2009
Stephen McDonald, Adam Chateauvert
Projection: UTM Zone 9
J. Hume, S. MacLellan
Datum: WGS84
NTS 1:50000 map Alastair Lake 103I3
No benchmark,
Benchmark:
Maximum depth: 79 m
moderate water levels
Surface Area: 6.85 km²
Long Axis: 8.4 km
Shoreline length: 20.8 km
Fig. 3a. Bathymetric chart of Alastair Lake.
54
Batchellor Lake
0
Batchellor Lake
500
1000
m
1500
53.6341º N 129.7067° W : Easting 9U 453267 Northing 5942833
Surveyed for:
Fisheries and Oceans, Canada
& Gitga'at First Nation
Surveyed by:
S. McDonald, DFO, C. Picard, Gitga'at
Base Map:
Drawn by:
Benchmark:
Surface Area:
2000
Survey Date:
Projection:
NTS 1:50000 map - Port Stephens 103H/5
J. Hume, S. MacLellan DFO
C Iron ring at SE end of lake - 5m away
from and 20 cm above water level
5.67 km²
Long Axis:
8.3 km
Datum:
July, 2006
UTM Zone 9
WGS84
Maximum depth:
132 m
Shoreline length:
18.8 km
Fig. 3b. Bathymetric chart of Batchellor Lake
55
Fig. 3c. Bathymetric chart of Bowser Lake.
56
0
0
24
47
70
52
80
47
83
20 50
58
56
88
78
89
97
91
95
97
97
100
0m
99
109
109
109
108
38
111
112
113
113
0
114
20
114
0
100
45
114
116
116
116
115
5000 m
Bowser Lake
113
50
59
0
101
71
115
115
115
0
114
56
108
108
108
20
20
10000 m
100 50
18
56.40 º N 129.43 ° W : Easting 9U 472382 Northing 6250844
Fisheries and Oceans, Canada
Survey Date: September 2009
Stephen McDonald, Adam Chateauvert
Projection: UTM Zone 9
J. Hume, S. MacLellan
Datum: WGS84
NTS 1:50000 map Bell Irving River 104A6
No benchmark,
Benchmark:
Maximum depth: 116 m
moderate water levels
Surface Area: 35.3 km²
Long Axis: 23.2 km
Shoreline length: 66.5 km
53
96
99
0
Bowser Lake
Surveyed for:
Surveyed by:
Drawn by:
Base map:
52
89
27
109
60
56
46
51
54
54
55
5656
56
56
36
37
9
55
8
56
21
21 21
21
8
14
0
58
21
20
18
25
22
7
25
19
25
17 11
50
7
52
0
30
16
56
51
58
60
22
0
11
11
15
17
8
10
0
16
11 8
0
9
7
30
20
28 2020
25
2327
29
7
11
28
28
28
29
2928
272624
28
0
13
26
26
22
0
0
0
0m
500 m
1000 m
Elbow Lake
34
Elbow Lake
Surveyed for:
52.06 º N 125.42 ° W : Easting 10U 315437 Northing 5773308
Fisheries and Oceans, Canada
Survey Date:
September 2007
Surveyed by:
Steve McDonald, Jeff Amos
Projection:
Drawn by:
J. Hume, S. MacLellan
Base map:
NTS 1:50000 map -Junker Lake 93C4
Benchmark:
Surface Area:
Fig. 3d. Bathymetric chart of Elbow Lake.
57
Datum:
C Campsite - no benchmark placed.
1.4 km²
Long Axis:
3.5 km
UTM Zone 9
WGS84
Maximum depth:
34 m
Shoreline length:
8.4 km
Fig. 3e. Bathymetric chart of Keecha Lake.
58
0
500
2000
0 m above water level.
& Campsite
Long Axis: 8.5 km
Surface Area:
3.5 km²
Benchmark:
C Benchmark - Iron ring in beach at shoreline,
J. Hume, S. MacLellan
NTS 1:50000 map -Port Stephens 103H5
Base map:
Steve McDonald, Rodney Harris
WGS84
UTM Zone 9
September 2008
38.2 km
Maximum depth: 65 m
Datum:
Projection:
Survey Date:
Shoreline (Inc. Islands) length:
53.30 º N 129.92 ° W : Easting 9U 438348 Northing 5905550
Fisheries and Oceans, Canada
1500
Drawn by:
Surveyed by:
Surveyed for:
Keecha Lake
1000
Keecha Lake
0m
500 m
1000 m
Kimsquit Lake
Kimsquit Lake
Surveyed for:
Surveyed by:
53.06 º N 127.24 ° W : Easting 9U 607050 Northing 5885264
Fisheries and Oceans, Canada
Survey Date:
September 2007
Steve McDonald, Jeff Amos
Projection:
Drawn by:
J. Hume, S. MacLellan
Base map:
NTS 1:50000 map - Foresight Mountain 93/E3
Benchmark:
Surface Area:
Datum:
C Iron ring at campsite 1.8 m above water
level
1.7 km²
Fig. 3f. Bathymetric chart of Kimsquit Lake.
59
Long Axis:
4.6 km
UTM Zone 9
WGS84
Maximum depth:
75 m
Shoreline length:
10.7 km
Kitlope Lake
Surveyed for:
53.06 º N 127.47 ° W : Easting 9U 581163 Northing 5883812
Fisheries and Oceans, Canada
Survey Date:
September 2007
Surveyed by:
Steve McDonald, Jeff Amos
Projection:
J. Hume, S. MacLellan
Drawn by:
Datum:
UTM Zone 9
WGS84
Base map:
NTS 1:50000 map -Kitlope Lake 93E4
C Campsite - no benchmark placed.
Benchmark: Water level about 2 m below high water
Maximum depth: 123 m
mark on rocks
Surface Area:
11.7 km²
Long Axis:
11.7 km Shoreline length:
28.4 km
0m
1000 m 2000 m
123
Kitlope Lake
Fig. 3g. Bathymetric chart of Kitlope Lake.
60
Koeye Lake
0
Koeye Lake
Surveyed for:
Surveyed by:
500
m
1000
51.77 º N 127.70 ° W : Easting 9U 589978 Northing 5736340
Fisheries and Oceans, Canada
Survey Date:
S. McDonald, Rodney Harris
Drawn by:
J. Hume, S. MacLellan
Base map:
NTS 1:50000 map - Namu 92M/13
C Iron ring at south side of campsite, 11 m
Benchmark:
Surface Area:
No
t
1500
from and 50 cm above waterline
4.5 km²
Long Axis:
6.6 km
Projection:
Datum:
August, 2006
UTM Zone 9
WGS84
Maximum depth:
63 m
Shoreline length:
14.8 km
ed
ey
rv
u
s
Fig. 3h. Bathymetric chart of Koeye Lake.
61
Fig. 3i. Bathymetric chart of Kooryet Lake.
62
Surface Area:
Benchmark:
5.1 km²
Long Axis: 6.2 km
0 m above water level.
& Campsite
1000
WGS84
UTM Zone 9
September 2008
46.8 km
Maximum depth: 63 m
Datum:
Projection:
Survey Date:
500
Shoreline (Inc. Islands) length:
NTS 1:50000 map -Port Stephens 103H5 & Banks lakes 103G8
Base map:
C Benchmark - Iron ring in beach at shoreline,
J. Hume, S. MacLellan
Steve McDonald, Rodney Harris
53.35 º N 129.98 ° W : Easting 9U 434490 Northing 5911022
Fisheries and Oceans, Canada
Drawn by:
Surveyed by:
Surveyed for:
Kooryet Lake
0
1500
Kooryet Lake
2000
Moore Lake
40
0
Moore Lake
Surveyed for:
Surveyed by:
53.41 º N 129.51 ° W : Easting 9U 465786 Northing 5918398
Fisheries and Oceans, Canada
Steve McDonald, Rodney Harris
Survey Date:
Projection:
Drawn by:
J. Hume, S. MacLellan
Base map:
NTS 1:50000 map -Port Stephens 103H5 & Hartley Bay 103H6
Datum:
Surface Area:
Long Axis: 6.2 km
1500
September 2008
WGS84
67
Maximum depth: 67 m
0 m above water level.
& Campsite
5.1 km²
1000
UTM Zone 9
C Benchmark - Iron ring in beach at shoreline,
Benchmark:
500
Shoreline (Inc. Islands) length:
46.8 km
Note:* Depths not corrected for saltwater detected at >20m in lower basin. Deeper depths in
this basin may be slightly deeper than shown.
Fig. 3j. Bathymetric chart of Moore Lake.
63
19 m
13 m
46 m
2m
13 m
Namu Lake
3m
0
500
1000
1500
m
22 m
Rock
55 m
58 m
Namu Lake
51.87 º N 127.83 ° W : Easting 9U 580493 Northing 5747328
Fisheries and Oceans, Canada
Surveyed for:
Survey Date:
S. McDonald, Rodney Harris
Surveyed by:
Projection:
Drawn by:
J. Hume, S. MacLellan
Base map:
NTS 1:50000 map - Namu 92M/13
C Iron ring at south side of campsite, 8 m
Benchmark:
Surface Area:
Fig. 3k. Bathymetric chart of Namu Lake.
64
from and 70 cm above waterline
3.2 km²
Long Axis:
5.7 km
Datum:
July, 2006
UTM Zone 9
WGS84
Maximum depth:
58 m
Shoreline length:
19.1 km
Fig. 3l. Bathymetric chart of Red Bluff Lake.
65
0
500
m
1000
1500
2000
Red Bluff Lake
126
Surface Area:
Projection:
Survey Date:
July, 2006
UTM Zone 9
from and 15 cm above water level
8.3 km²
Long Axis:
11.0 km
Shoreline length:
Maximum depth:
30.0 km
199 m
J. Hume, S. MacLellan DFO
Datum:
WGS84
Satellite photograph from Google Earth (http:/earth.google.com) Sept. 2006.
C Iron ring at island in narrows 33 m away
Benchmark:
Base map:
Drawn by:
S. McDonald, DFO, C. Picard, Gitga'at
Surveyed by:
53.47 º N 129.58 ° W : Easting 9U 461260 Northing 5924223
Fisheries and Oceans, Canada
& Gitga'at First Nation
Surveyed for:
Red Bluff Lake
199
195
Tankeeah Lake - Lower
0
250
500
750
1000
m
Tankeeah Lake - Lower
Surveyed for:
52.32 º N 128.27 ° W : Easting 9U 549756 Northing 5796223
Fisheries and Oceans, Canada
Survey Date:
August, 2006
Surveyed by:
S. McDonald, Rodney Harris
Projection:
Drawn by:
J. Hume, S. MacLellan
Base map:
NTS 1:50000 map - Spiller Channel 103A/8
Benchmark:
Surface Area:
Datum:
no benchmark, lake level was high
1.5 km²
Longest Axis:
2.1 km
UTM Zone 9
WGS84
Maximum depth:
29 m
Shoreline length:
14.75 km
Fig. 3m. Bathymetric chart of Tankeeah Lake (lower)
66
16
Tankeeah Lake - Upper
0
200
400
600
24
m
23
26
32
Tankeeah Lake - Upper
Surveyed for:
52.20 º N 128.16 ° W : Easting 9U 550374 Northing 5799187
Fisheries and Oceans, Canada
Survey Date:
August, 2006
Surveyed by:
S. McDonald, Rodney Harris
J. Hume, S. MacLellan
NTS 1:50000 map - Spiller Channel 103A/8
Benchmark:
C benchmark, 3m from shore, 10cm above
Surface Area:
19
Fig. 3n. Bathymetric chart of Tankeeah Lake (upper).
67
Projection:
Drawn by:
Base map:
1.3 km²
waterline
Longest Axis:
Datum:
3.0 km
UTM Zone 9
WGS84
Maximum depth:
32 m
Shoreline length:
10.2 km
20
2x2m trawl (n=847)
gill nets (n=169)
Frequency (%)
16
12
8
4
0
20
32
44
56
68
80
92
104
116
128
140
152
Length (mm)
Fig 4a. Length frequency of all O. nerka caught during September surveys (17 lakes) using the
small trawl and Swedish gill nets. Eight larger kokanee (>180 mm) caught by gillnets are not
displayed. Data was grouped into 3 mm length bins for plotting.
20
2x2m trawl (n=847)
3x7m trawl (n=598)
Frequency (%)
16
12
8
4
0
20
32
44
56
68
80
92
104
116
128
140
152
Length (mm)
Fig 4b. Length frequency of all O. nerka caught during September surveys (17 lakes) using the
large and small trawls. Data was grouped into 3 mm length bins for plotting.
68
O. nerka Diets by Water Type
Mean # of Prey items/fish
600
500
400
300
200
100
0
Mean Prey Biomass (mg/fish)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Zooplankton
Terrestrial Insects
Stained
Clear
Macroinvertebrates
Glacially Turbid
Fig 5. General components of the diet of age-0 and age-1 O. nerka averaged for each of the 3
lake types by abundance and by biomass. Diet data from this study and from Hume and
MacLellan (2008) were pooled for this analysis. The biomass of terrestrial insects is not
reliably measured. Macro-invertebrates includes Chaoborus, Chironomid, and
Ceratopogonid larvae, Neomysis, worms, and amphipods.
69
Zooplankton in O. nerka Diets by Water Type
400
Mean # of Prey Items/fish
350
300
250
200
150
100
50
0
Mean Prey Biomass (mg/fish)
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Bosmina
Calanoida
Cyclopoida
Clear
Daphniidae
Glacially Turbid
Holopedium
Other
Cladocera
Stained
Fig 6. Zooplankton components of the diet of age-0 and age-1 O. nerka averaged for each of the
three lake types by abundance and by biomass. Diet data from this study and from Hume
and MacLellan (2008) were pooled for this analysis.
70
Stickleback Diet
120.0
M ean # of Diet Item s/Fish
100.0
80.0
60.0
40.0
20.0
0.0
Bosmina
Calanoida
Cyclopoida
Daphniidae
Holopedium
Stained (mean of 12 Lakes)
Macro
Invertebrate
Other
Cladocera
Terrestrial
Insect
Clear (Alastair Lake)
Fig. 7. Stickleback diet in stained and clear lakes. The values for stained lakes are an average of
12 lakes, whereas the clear lake values are from only one lake (Alastair Lake).
71
Fish Diet - Stained Lakes
# of diet items/fish
0
100
200
300
400
500
600
700
800
900
Banks East
--> 1170
Banks West
--> 1666
Ecstall
Evelyn
Keecha
Kitkiata
Koeye
--> 1091
Kooryet
Moore
Namu
Red Bluff
Tankeeah Lower
Tankeeah Upper
Fish Diet - Clear Water Lakes
0
100
200
300
400
500
600
700
800
900
Alastair
--> 1928
Azuklotz
Bear
Elbow
--> 1586
Fred Wright
--> 1131
Johanson
Johnston
Kimsquit
Kitlope
Kitwanga
Lakelse
Lonesome
McDonell
Meziadin
Morice
Slamgeesh
-->1355
Stephens
Sustut
Swan
Fish Diet - Glacial Turbid Lakes
0
100
200
300
400
500
600
700
800
900
Bowser
Kitsumkalum
Motase
Calanoida
Other Cladocera
Cyclopoida
Terrestrial Insects
Holopedium
Bosmina
Macro Invertebrates
Daphniidae
Fig. 8. Estimated abundance of prey items for age-0 O. nerka from lake surveys. Includes lakes
covered by this report and Hume and MacLellan (2008).
72
Fish Diet - Stained Lakes
Mean weight (mg) of diet items/fish
0
1
2
3
4
5
6
7
8
9
10
11
12
Banks East
Banks West
Ecstall
Evelyn
Keecha
Kitkiata
Koeye
Kooryet
Moore
Namu
Red Bluff
Tankeeah Lower
Tankeeah Upper
Fish Diet - Clear Water Lakes
0
1
2
3
4
5
6
7
8
9
10
11
12
Alastair
Azuklotz
--> 12.4
Bear
--> 14.3
Elbow
Fred Wright
Johanson
Johnston
Kimsquit
Kitlope
Kitwanga
Lakelse
Lonesome
McDonell
Meziadin
Morice
--> 16.8
Slamgeesh
Stephens
Sustut
Swan
Fish Diet - Glacial Turbid Lakes
0
1
2
3
4
5
6
7
8
9
10
11
12
Bowser
Kitsumkalum
Motase
Calanoida
Other Cladocera
Cyclopoida
Terrestrial Insects
Holopedium
Bosmina
Macro Invertebrates
Daphniidae
Fig. 9. Estimated biomass of prey items for age-0 O. nerka from lake surveys. Includes lakes
covered by this report and Hume and MacLellan (2008).
73
Alastair Lake (O. nerka ) - September 13/2009
24
Frequency
20
16
12
8
4
0
20
32
44
56
68
80
92
104
116
128
Length (mm)
Trawls
Gill Nets
Bowser Lake (O. nerka ) - September 4/2009
24
Frequency
20
16
12
8
4
0
20
32
44
56
68
80
92
104
116
128
Length (mm)
Trawls
Gill Nets
Elbow Lake (O. nerka ) - September 20/2007
5
Frequency
4
3
2
1
0
20
35
50
65
80
95
110
125
140
155
Length (mm)
Trawls
Gill Nets
Fig. 10. Length frequency histograms of O. nerka from each survey
74
170
185
200
Fred Wright Lake (O. nerka ) - September 9/2009
4
Frequency
3
2
1
0
20
32
44
56
68
80
92
104
116
128
Length (mm)
Trawls
Gill Nets
Keecha Lake (O. nerka ) - September 4/2008
35
Frequency
30
25
20
15
10
5
0
20
32
44
56
68
80
92
104
116
128
116
128
Length (mm)
Trawls
Kimsquit Lake (O. nerka ) - September 13/2007
8
7
Frequency
6
5
4
3
2
1
0
20
32
44
56
68
80
92
104
Length (mm)
Trawls
Gill Nets
Fig. 10. Length frequency histograms of O. nerka from each survey (continued).
75
Kitlope Lake (O. nerka ) - September 15/2007
24
Frequency
20
16
12
8
4
0
20
32
44
56
68
80
92
104
116
128
116
128
116
128
Length (mm)
Trawls
Gill Nets
Koeye Lake (O.nerka ) - September 12/2006
20
Frequency
16
12
8
4
0
20
32
44
56
68
80
92
104
Length (mm)
Trawls
Kooryet Lake (O. nerka ) - September 1/2008
14
12
Frequency
10
8
6
4
2
0
20
32
44
56
68
80
92
104
Length (mm)
Trawls
Fig. 10. Length frequency histograms of O. nerka from each survey (continued).
76
Kwinageese Lake (O. nerka ) - September 7/2009
4
Frequency
3
2
1
0
20
32
44
56
68
80
92
104
116
128
Length (mm)
Trawls
Gill nets
Lonesome Lake (O. nerka ) - September 8/2007
20
Frequency
16
12
8
4
0
20
35
50
65
80
95
110
125
Length (mm)
Trawls
140
155
170
185
200
Gill Nets
Meziadin Lake (O. nerka ) - September 17/2009
80
70
Age-0
Age-1
Frequency
60
50
40
30
20
10
0
20
32
44
56
68
80
92
104
116
Length (mm)
Trawls
Fig. 10. Length frequency histograms of O. nerka from each survey (continued).
77
128
Moore Lake (O. nerka ) - September 7/2008
40
35
Frequency
30
25
20
15
10
5
0
20
32
44
56
68
80
92
104
116
128
116
128
116
128
Length (mm)
Trawls
Morice Lake (O. nerka ) - September 22/2009
5
Frequency
4
3
2
1
0
20
32
44
56
68
80
92
104
Length (mm)
Trawls
Namu Lake (O. nerka ) - September 15/2006
8
7
Frequency
6
5
4
3
2
1
0
20
32
44
56
68
80
92
104
Length (mm)
Trawls
Gill Nets
Fig. 10. Length frequency histograms of O. nerka from each survey (continued).
78
Red Bluff Lake (O. nerka ) - July 23/2006
5
Frequency
4
3
2
1
0
20
32
44
56
68
80
92
104
116
128
140
152
164
176
Length (mm)
Trawls
Gill Nets
Tankeeah Lower Lake (O. nerka ) - September 18/2006
8
7
Frequency
6
5
4
3
2
1
0
20
32
44
56
68
80
92
104
116
128
Length (mm)
Trawls
Gill Nets
Tamkeeah Upper Lake (O. nerka ) - September 19/2006
4
Frequency
3
2
1
0
20
32
44
56
68
80
92
104
116
Length (mm)
Trawls
Fig. 10. Length frequency histograms of O. nerka from each survey (continued).
79
128
Whalen Lake (O. nerka ) - July 26/2006
10
Frequency
8
6
4
2
0
20
32
44
56
68
80
92
104
116
Length (mm)
Trawls
Gill Nets
Fig. 10. Length frequency histograms of O. nerka from each survey (continued).
80
128
APPENDICES
APPENDIX 1. INDIVIDUAL LAKE REPORTS
Here we present general descriptions of each of the study lakes and the surveys, including
highlights, difficulties encountered and how they were handled, and a description of the pelagic
fish communities found. We also evaluate each lake’s suitability for hydroacoustic assessment
and recommend strategies for any future surveys on these lakes. For detailed survey results see
the various tables, figures and appendices within this document.
Alastair Lake
Alastair Lake is located in the lower Skeena River drainage. The Gitnadoix River drains
Alastair Lake and runs 20 km to the north, joining the Skeena River about 50 km from the
Pacific Ocean. With an elevation of only 45 m above sea level, and a relatively short distance
from salt water, its not surprising that harbour seals were observed in the lake during the survey
in 2009. We surveyed this lake on September 13, 2009 with the Little Echo and the 2x2 m trawl.
Initially we used an existing bathymetric chart (Simpson et al. 1981) but found it did not agree
well with data from our hydroacoustic survey transects, so we developed a new chart from our
survey transects plus data recorded during trawls (Fig. 3a).
Alastair was classified as a clear lake. We divided it into two sections; section one to the
south is a deep basin with a maximum depth just under 80 m; to the north, section two is larger
in surface area but much shallower with a maximum depth of 26 m (Fig 2a and 3a). The pelagic
fish community of Alastair was dominated by threespine stickleback, with stickleback densities
ranging from 4 900/ha in section 2 to 7 600/ha in section 1. O. nerka densities were relatively
consistent throughout the lake at 544/ha. Stickleback lengths ranged from 14-71 mm with two or
three size classes present. O. nerka were present in two age classes; Age-0 fish ranging from 3764 mm in length and Age-1 fish from 63-86 mm length. Daphnia, juvenile sockeye’s preferred
food, made up <2% of the zooplankton community, most likely the result of cropping by the
many planktivores in the lake, while Bosmina accounted for 72% of the zooplankton community
(Appendix 6). O. nerka diet reflected these ratios with their diet consisting mainly of Bosmina
(70-80%) and stomach fullness estimates ranging from 2% to 25% (Appendix 5). These results
are consistent with those found in an October 1995 survey, where it was determined much of the
potential sockeye rearing capacity of this lake was taken up by the stickleback population
(Shortreed et al. 1998).
This lake is suitable for hydroacoustic assessment of pelagic fish populations. However,
with large numbers of stickleback present, it is important to conduct extensive trawling to
establish the relative proportions of stickleback and O. nerka, both in different areas of the lake,
and at different depth layers. In our survey we found in section 1 (the deep section), that
stickleback dominated the top 12 m of the water column, and O. nerka dominated below that
81
level. In section 2 (the shallower section) the two species seemed to be more mixed throughout
the water column. Also, because of the high densities of stickleback present in the upper depth
strata, trawls targeting deeper strata are subject to significant contamination during deployment
and retrieval of the net, and this contamination needs to be estimated in some manner. We
estimated catch rates from trawls in the various depth layers and then estimated the time the net
spent in those layers during deployment and retrieval to calculate contamination from shallower
fish layers. To best accomplish this, detailed records on start and finish, time and position for
each trawl, and of net depth over time must be recorded. A closing trawl system would be of
great benefit to any survey on this lake, eliminating the need to estimate net contamination.
For future surveys of Alastair, transect 8 should be moved a little to the south, to take
advantage of deeper water and avoid large woody debris which hampered navigation along its
present course.
Batchellor Lake
We surveyed Batchellor Lake on July 20, 2006 with the Little Echo and the 2x2 m trawl.
The purpose of this survey was to assess the lake’s suitability for raising transplanted sockeye fry
(Hanging Lakes Program). The lake is situated on the north coast of British Columbia, about 75
km northwest of Hartley Bay, and runs near and parallel to Grenville Channel. The lake drains
via Batchellor Creek, which includes a barrier to anadromous fish, a short distance from
Grenville Channel. We used survey and additional transects, along with additional soundings to
construct a bathymetric chart for the lake (Fig. 3b). Batchelor Lake, like most of our coastal
lakes, was classified as stained.
No O. nerka were detected in the lake. Our trawls caught no fish in the pelagic zone of
Batchellor Lake but other gear caught a number of Dolly Varden and cutthroat trout (Tables 3
and 4). Chaoborus was found to be present, with highest densities toward the south end of the
lake. Therefore acoustic data collection and processing was done using Chaoborus methods
outlined in MacLellan and Hume (2010).
Batchellor Lake’s morphology lends itself well to hydroacoustic assessments. However,
future surveys will need to prepare for and deal with interference from Chaoborus larva when
estimating fish abundance.
Bowser Lake
Bowser Lake is located about 60 km north of Stewart, B.C. and is in the interior of
northern British Columbia, within the Nass River drainage. Although the Kitimat-Cassiar
Highway passes close by, there was no road access, so we flew in by float plane and used the
Little Echo with its 2x2 m trawl on September 4, 2009. Bowser is glacially turbid with turbidity
82
values ranging from 18 to 60 NTU (Table 1), making this lake second only to Motase Lake as
the most turbid lake we have worked on. Initially we used an existing bathymetric chart (FIDQ),
but found it matched poorly with the transect soundings. Therefore we generated a chart based
on the transect and trawl soundings along with some extra soundings taken just for this purpose
(Fig. 3c).
With such high turbidity levels it’s not surprising to see fish (O. nerka) behaving
differently from what we see in relatively clear lakes. We found the O. nerka of Bowser Lake
were behaving similar to those in Motase Lake (Hume and MacLellan 2008). These fish were
extremely surface oriented, to such an extent as to make downward looking acoustics virtually
useless. Hydroacoustics detected only a handful of fish throughout the entire survey, yet surface
trawls produced 49 O. nerka of various ages (Table 3). Age-0 O. nerka averaged 52 mm in
length and age-1 O. nerka averaged 70 mm. The surface trawls also indicate higher densities of
O. nerka near shore, usually where water depth was less than 20 m. Since most of the O. nerka
population was in the top 4 m of the water column, we used densities derived from the surface
trawls to estimate O. nerka abundance. Densities were calculated for near shore and off shore
areas of the lake and extrapolated for the whole lake to produce an abundance estimate of
131 000 O. nerka. Because of the limited sampling power of trawls relative to the whole lake,
the reliability of this estimate is very low.
The diet of Bowser fish is similar to those of other glacial turbid lakes we have worked
on, with a heavy reliance on terrestrial insects (Fig. 9). Although the estimation of insect
biomass is uncertain relative to zooplankton biomass, the data clearly indicate that insects play a
much more important role in juvenile sockeye diet in these glacially turbid lakes than in clear
lakes. Perhaps this reliance on insects is what attracts these normally pelagic fish into more
littoral habitat near shore. O. nerka diet and consequently growth and productivity appears to be
associated more with the terrestrial environment and consequently production models based on
the lake habitat such as the PR model are not appropriate.
Bowser Lake is not a good candidate for traditional (down looking) hydroacoustic
assessment techniques. Fish behavior puts most of the population in the top 4 m of the lake, an
area of the lake unseen by the transducer. A trawl survey is an option, but would require a great
deal of effort to produce reliable results. Side looking acoustics is another option and should be
investigated, but it is not without its own set of challenges, related to techniques, interpretation
and calibration.
Elbow Lake
Elbow Lake is in the Bella Coola region of central British Columbia, about 86 km
southeast of the town of Bella Coola and is within the boundaries of Tweedsmuir Provincial
Park. This lake is the furthest lake up the Atnarko River Valley, and although glacially
influenced, was rated clear because its range of turbidity readings fell below 5 NTU (Table 1).
83
We surveyed this lake on September 19, 2007 using the Little Echo and the 2x2 trawl. Using
transect and additional soundings we created a bathymetric chart for the lake. The lake is
relatively small, only 3.5 km long with a surface area of 1.4 km2 (Fig. 2d). We excluded the
shallow lower part of the lake (1 km long, max. depth 6 m) from the survey as it was unlikely to
hold significant numbers of O. nerka. Exploratory transects detected no fish in that section of
the lake and few fish were detected above 10 m in the deeper southern basin.
A surface trawl caught only a few small sculpins, which were unlikely large enough to be
detected by the sounder at our data processing threshold. Other trawls caught 11 juvenile O.
nerka and one juvenile coho. Gill nets caught a few northern pikeminnow and a mixture of O.
nerka age classes, including some adult kokanee. We were not able to determine ratios of
sockeye and kokanee within the juvenile O. nerka population. Daphnia were present in good
numbers in this lake and as expected they were the most important item in the diet of Elbow
Lake O. nerka (Fig. 8 and 9).
With the shallow section of this lake eliminated from consideration, Elbow Lake is easily
surveyed using hydroacoustics and should produce reliable results. The only difficulty here is
identifying juvenile sockeye from juvenile kokanee in the trawl and gill net samples.
Fred Wright Lake
Fred Wright Lake lies within the Nass River watershed in the interior of northern British
Columbia about 78 km east of Stewart, B.C. It is drained by the Kwinageese River which runs
north for 25 km until it joins the Nass River. Fred Wright is classified as clear, and we surveyed
it on September 9, 2009 using the Little Echo and the 2x2 m trawl. We used a bathymetric chart
produced by the Fish and Wildlife Branch in 1973 (FIDQ).
Trawls caught only two juvenile O. nerka and two sculpin. Gill nets were also low,
catching only six O. nerka (4 age-1, 2 age-0) (Table 3). The only other fish caught was a large
bull trout. Hydroacoustics detected only scattered targets throughout the lake, indicating no
major sockeye population residing in the lake. A layer of fish was found in the arms at the south
end of the lake. However, this layer is shallow (0-8 m) and somewhat shore oriented, so it is
unlikely to consist of many, if any, O. nerka. Any future surveys might look for this assemblage
and target it with trawl and gill nets to confirm what species is present. Daphnia were the most
important food item found in the few O. nerka we did capture.
With such low densities of fish detected and the correspondingly low trawl catches, our
confidence in the tracked target estimate of 45 000 O. nerka (Appendix 3) is low, although the
estimate is reasonable when compared to recent acoustic surveys and trends for this stock.
Estimates of age-0 sockeye in Fred Wright in previous years (1978-2004) have ranged from
41 069 to 648 500 fish and smolt studies in the Kwinageese River indicate the majority of
migrating sockeye are age-1 fish (Bussanich 2005, Hall et al. In Prep), suggesting a four year life
cycle for Fred Wright Lake sockeye. The 2009 estimate is the second lowest on record, but is
84
consistent with the last acoustic survey conducted on this cycle (41 069 sockeye in 2001) and is
consistent with the overall decline of adult spawners in recent years (Hall et al. In Prep).
The lake lends itself well to hydroacoustic assessment, and should substantial numbers of
juvenile sockeye be rearing in the lake in the future, an acoustic survey should provide reliable
estimates of O. nerka abundance.
Keecha Lake
Keecha Lake is located on the north coast of British Columbia on Banks Island. The lake
is 8.5 km long, with many islands, and drains a short distance east into Principe Channel. We
surveyed Keecha on September 4, 2008 with the Little Echo and the 2x2 m trawl. Keecha was
classified as stained. We created a chart for this lake using survey transects, additional transects
approximately half way between the survey transects, and additional soundings around larger
shoal areas (Fig. 3e).
Chaoborus larva are present in Keecha Lake. They were captured by SCOR nets and
they are evident on some echograms. The distribution of Chaoborus around the lake appears to
be quite patchy, with some transects showing areas of moderate to high densities, and other
transects showing no Chaoborus at all (at fish analysis thresholds). Where detected by the
acoustics, Chaoborus was usually found in the top 15 m of the water column. Because
Chaoborus is present in acoustically detectable densities, integration analysis was not used.
Instead, Chaoborus–TT methods were used to estimate fish abundance (MacLellan and Hume
2010).
Both stickleback and O. nerka inhabited the pelagic zone of Keecha Lake. Trawls
indicated both were vertically stratified with overlapping ranges. Threespine stickleback
predominated in the shallower layers of the water column. Stickleback were rather large in this
lake, as large and sometimes larger than the age-0 O. nerka. Of the 202 juvenile O. nerka
caught, only five were age-1 fish, the remainder were age-0. Other species caught, besides
stickleback, were Dolly Varden and sculpin (Tables 3 and 4). With Daphnia notably absent
from the zooplankton community in Keecha Lake, O. nerka diet consisted mainly of Bosminidae
and Diaptomus, along with some terrestrial insects.
Keecha is a multibasin lake with numerous islands and shoals, which makes night time
navigation and trawling (in some areas of the lake) challenging. With both Chaoborus and
abundant stickleback in the lake, hydroacoustic data collection and analysis need to be modified
to use Chaoborus techniques (MacLellan and Hume 2010) and trawling needs to be expanded, to
not only cover all basins, but several depth strata within each basin to get good estimates of O.
nerka/stickleback ratios for the various depth strata. With these extra efforts, hydroacoustic
surveys of this lake should produce reasonable estimates of O. nerka abundance.
85
Kimsquit Lake
Kimsquit Lake is located in the mountains northeast of the Kitlope River at an elevation
of 358 m and drains east and then south for about 46 km to the top end of Dean Channel. While
there are several ice fields in close proximity of Kimsquit Lake, the lake was apparently not
affected by glacial melt waters (0.1 NTU) and was classified clear (Table 1). We surveyed this
lake using the Little Echo and the 2x2m trawl on September 13, 2007. From our transect
acoustics and additional soundings we produced a bathymetric chart of the lake (Fig. 3f).
The fish in Kimsquit, which were almost all O. nerka, were distributed fairly evenly over
most of the lake, and at a relatively shallow depth of 4-10 m. Fish densities did not appear to
extend to the surface and a surface trawl (0-2 m) caught no fish. Other trawls and gillnets caught
a total of 50 O. nerka and one sculpin (Tables 3 and 4). O. nerka were present in three size
classes and scale aging indicated that the two smaller size classes were both age-0 and the largest
class was age-1. This distribution of sizes and ages suggests the presence of a kokanee
population in the lake as well as anadromous juvenile sockeye. Diet information indicates
Holopedium and insects are important in the diets of Kimsquit O. nerka (Appendix 5).
Over all, Kimsquit Lake is well suited to hydroacoustic surveys due to its deep waters
and the predominance of O. nerka in the fish population. The only concerns are with respect to
the shallow distribution of the fish which is nearing the limits of detection for downward looking
transducers and estimating the proportion of sockeye verses kokanee within the O. nerka
population.
Kitlope Lake
Kitlope Lake is located in the north coast region of British Columbia and is within the
Kitlope Heritage Conservancy Protected Area. It is located only 10 km from salt water at the
head of Gardner Canal, yet it is quite some distance from the Pacific Ocean and thus exhibits a
mix of climate characteristics typical of the coast and the interior coastal mountains (Stockner et
al. 1993). At only 13 m above sea level, seals have easy access to the lake and were observed
during the survey. We surveyed Kitlope on September 15, 2007 using the Little Echo and 2x2 m
trawl. We generated a bathymetric chart from the survey transect data, supplemented with some
additional soundings (Fig. 3g).
We classified Kitlope as clear because turbidity was well below 5 NTU at the time of our
survey. However, this lake has shown large variations in water clarity in the past, both spatially
and seasonally, due to its fast flushing rate and dynamic surface circulation patterns and the way
they distribute the glacially turbid water from the Tezwa River (Stockner et al. 1993). Stockner
recorded Secchi depths as low as 1 m with a compensation depth of 3.7 m during their 3 year
study of the lake. These values are often associated with turbidity readings over 5 NTU, which
indicates that this lake would occasionally qualify for the glacially turbid category.
86
Trawls caught 100 age-0 O. nerka with a mean length of 50 mm and 10 age-1 O. nerka
with a mean length 72 mm (Table 3). Simpson et al. (1981) found similar sized fall fry in 1978
with a mean length of 48 mm. Stockner et al. (1993) suggested that the juvenile sockeye in
Kitlope Lake were found in the top 10 m of the water column. Our survey found much of the O.
nerka population was in the top 2-3 m of the lake. Since our acoustics do not adequately sample
this region of the water column we calculated density for the 0-2 m strata from our surface trawl
catches. A comparison between hydroacoustic and trawl net derived density for the top most
ensonified layer (2-4 m) was favorable, so we have some confidence in the surface strata density
estimate derived from surface trawls. Other species present in our trawl catches were threespine
stickleback and sculpin, but these species were a very minor portion of the pelagic community.
Eubosmina and insects were important diet items for the O. nerka of Kitlope Lake.
Kitlope Lake is a relatively noisy environment (hydroacoustically) with a fair bit of
interference from bubbles, currents and debris. This limitation, coupled with fish behavior and
their preference for occupying the surface layers, makes this lake only marginally suitable for
hydroacoustic surveys. Future surveys need to adequately assess the surface layers of Kitlope
Lake. The acoustic interference present in the lake may make surface trawls the preferred
method of assessing the surface layers rather than side looking acoustic technology. In any case,
all acoustic data will likely contain a fair bit of noise which will have to be removed through
editing.
Koeye Lake
Koeye Lake was classified as a stained lake and is situated on the central coast of British
Columbia about 14 km southeast of Namu. It is 53 m above sea level and the outlet flows 10 km
west into Fitz Hugh Sound. We surveyed Koeye on September 12, 2006 using the Little Echo
and the 2x2 m trawl. A log jam at the outlet of the lake prevented us from including Little
Koeye Lake in the survey. A bathymetric chart was generated from the survey and additional
soundings of the lake (Fig. 3h).
Chaoborus larva were present on all transects of this lake and in relatively high densities
on several transects. Because echoes from these larvae interfere with and overlap with fish
echoes, we used a modified tracked target analysis (MacLellan and Hume 2010) to estimate fish
abundance at about 484 000 O. nerka (Appendix 3).
The trawl caught 71 fish (Appendix 2); all but one were juvenile O. nerka averaging 53
mm in length, indicating that most fish in the pelagic zone are O. nerka. Gill net sets caught no
fish. The pelagic fish and zooplankton communities of this lake are more typical of clear water
lakes than stained, with O. nerka dominating and Daphnia present in good numbers. Daphnia
was the most important diet item for age-0 O. nerka.
This lake has ample depth and a simple pelagic fish community, normally making it a
good candidate for hydroacoustic surveys. However the presence of Chaoborus in the water
87
column is a complicating factor. Modified Chaoborus techniques need to be considered both
during data collection and data analysis (MacLellan and Hume 2010). As long as these modified
techniques are employed and the Chaoborus densities are not too great, estimates of pelagic fish
abundance are possible.
Kooryet Lake
Kooryet Lake is located on the north coast of British Columbia, on the eastern side of
Banks Island, 4 km north of Keecha Lake. Due to the close proximity of these two lakes, they
share many physical characteristics including having multiple basins with many islands and
shoals. Kooryet Lake is about 6.2 km long, with an additional 2.5 km of outlet shallows (not
surveyed) that drain a short distance to Principe Channel. We surveyed Kooryet with the Little
Echo, using the 2x2 m trawl on September 1, 2008. Like most coastal lakes, Kooryet is a stained
lake. We produced a bathymetric chart of the lake from the survey soundings (Fig. 3i).
Surprisingly, given this lake’s close proximity to Keecha Lake, no Chaoborus larva were
detected in Kooryet’s water column, either in the SCOR net samples or by the echo sounder.
The pelagic fish community of Kooryet Lake was much the same as found in Keecha Lake, a
mixture of O. nerka and threespine stickleback, with each species vertically stratified and
overlapping to some degree. Similar to Keecha, the stickleback of Kooryet were quite large,
most being larger than age-0 O. nerka (Tables 3 and 4). O. nerka diet differed slightly from
Keecha, in that the calanoid copepod, Epischura, was an important diet item for Kooryet O.
nerka.
Like Keecha Lake, Kooryet is suitable for hydroacoustic assessment for O. nerka
abundance, if considerable effort is spent on trawling to determine O. nerka/stickleback ratios in
the various depth strata of each basin.
Kwinageese Lake
Kwinageese Lake lies in the Nass River watershed of northern British Columbia, about
78 km east of Stewart, B.C. It drains south 3.8 km, via the Kwinageese River, to Fred Wright
Lake. We surveyed this lake on September 7, 2009 using the Little Echo and the 2x2m trawl.
Kwinageese is classified as a clear lake. We used an existing bathymetric chart produced in
1996 for this survey (FIDQ).
Trawls and gill nets caught only three O. nerka; one each of age-0, age-1 and age-2+.
The only other species caught in trawls were juvenile coho. Gill nets also caught rainbow trout,
lake chub, and redside shiners (Tables 3 and 4). Hydroacoustics detected very few targets.
Since the initial survey was conducted under a bright moon, to make sure this was not the source
of a lack of targets, we resurveyed several transects the following night under overcast skies.
88
Subsequent analysis detected little difference between the first and second night’s transects. No
diet analysis was done due to the small sample size. Confidence of our estimate of around 6 000
O. nerka for the lake is low, given the low number of detections by the echo sounder and poor
catch by our sampling gears. It is clear however, that there were very few juvenile O. nerka
rearing in the lake in 2009, and many of them may well be kokanee given the presence of the
older age classes captured in our gill nets and by Hill et al. (1997a, 1997b). Sockeye smolts were
documented leaving the lake in the early 1990’s, but recently beavers have heavily damned the
outlet to Kwinageese River, making fry and adult sockeye access to the lake unlikely (Hall et al.
In press).
Although a complicated bathymetry makes for an atypical survey design on this lake,
hydroacoustics should be effective in estimating O. nerka abundance if they are present in
greater numbers.
Lonesome Lake
Lonesome Lake is in the central interior, Bella Coola region, of British Columbia, about
72 km east of the town of Bella Coola, within Tweedsmuir Provincial Park. Part of the Atnarko
River system, Lonesome Lake is just 14 km downstream from Elbow Lake. We surveyed
Lonesome Lake with the Little Echo and the 2x2 m trawl. With its low turbidity readings, this
lake was classified as clear, although there is some glacial influence to its waters. We used a
Fish and Wildlife Branch bathymetric chart (FIDQ) drafted in 1976 for our survey design and
lake volume calculations. Lonesome is approximately 9 km long, however, the first 4 km from
the inlet end is relatively shallow (<6 m maximum depth) with many macrophytes present. It is
unlikely that these shallows hold O. nerka in significant numbers. Therefore, these southern
shallows were not included in the survey.
Trawls and gill nets caught 81 O. nerka in total. Most were age-0, but some were age-1
and age-2+ (Table 3), indicating a kokanee population is rearing in the lake as well as juvenile
sockeye. We were not able to distinguish between age-0 sockeye and age-0 kokanee. Other
species caught were sculpin, rainbow trout, cutthroat trout, and northern pikeminnow. Fish in
the pelagic zone were dispersed, generally from 10 m to the bottom through the deep basin of the
lake (Section 1). We estimated approximately 130 000 juvenile O. nerka in the lake. Lonesome
Lake O. nerka fed mainly on Daphnia.
The deep basin of Lonesome lake is well suited for hydroacoustic assessment for juvenile
sockeye. The challenge is distinguishing between juvenile sockeye and juvenile kokanee in
trawl samples to apportion the O. nerka abundance estimate. There is a hint of bimodality in the
length distribution within the trawl samples, but there is clearly much overlap. DNA or otolith
strontium analysis would be needed to proportion sockeye/kokanee with any reasonable degree
of confidence.
89
Meziadin Lake
Meziadin Lake is the rearing lake for the single largest sockeye stock in the Nass River
System. It is located along the Cassiar Highway and approximately 45 km east of Stewart, B.C.
We surveyed this lake on September 17, 2009, using the Night Echo (7.3 m cabin cruiser) and
our 3x7 m trawl net. Although Meziadin is definitely glacially influenced, we classified it as
clear due to relatively low turbidity readings (<5 NTU) (Table 1). For planning and lake volume
calculation we used an existing bathymetric chart produced by the Fish and Wildlife Branch in
1972 (FIDQ).
Past surveys of this lake have been plagued with high 95% confidence limits in fish
abundance estimates, most likely driven by the varied fish densities encountered in this relatively
large lake. We found such fish distributions in our survey, with quite low densities in the
northern section of the lake, and very high densities to the south. In order to try to constrain
confidence limits, our survey design increased the number of transects from the six used in past
surveys to ten. In addition we stratified the design, dividing the lake into two sections of five
transects each. Even so, our O. nerka estimate of 9 000 000 has confidence limits on the high
side at +/- 53% (Appendix 3).
We found that the vertical distribution of juvenile sockeye on most transects appeared to
extend right up to the near surface ensonification limits of the transducer. This leaves the
possibility that significant numbers of fish were present in the surface layers (0-2 m, 2-4 m) that
are not detectable by the sounder due to transducer draft, transducer near field, and in this case
surface noise that, at times, extended into the 2-4 m layer. This resulted in no useful acoustic
information collected in these layers. Some acoustic information was gathered during trawls and
since the transducer uses less draft during trawls and there is less surface noise, we were able
estimate densities for the 2-4 m layer and gain some insight into their magnitude relative to
adjacent layers. In section 1, densities from trawl soundings for the 2-4 m layer tended to be
similar to the layer below, so we used densities from the layer below to estimate densities in the
2-4 m layer on transects. Similarly, for section 2, we found trawl acoustic densities for the 2-4 m
layer to be roughly half that of the layer below, so for these transects, we used 50% of the
density from the 4-6 m layer to estimate density in the 2-4 m layer. To estimate densities in the
top layer (0-2 m) we looked to our surface trawls (1 in each section) for information. The net is
7 m deep so it fishes the top four layers (0-8 m) of the water column. After calculating expected
catch from the lower 3 layers (2-8 m) using trawl acoustic densities and a net efficiency based on
deeper trawls (~70%), we determined that our actual catch could be accounted for from the three
lower layers alone. This was the case in both sections, suggesting few fish are in the top 2 m
layer, so no density was applied to it.
Trawls caught 1 042 fish, that were all O. nerka except for one whitefish. The O. nerka
catch was comprised of two age classes, 701 (67%) age-0 fish and 340 (33%) age-1 fish
(Appendix 2). We retained 576 of these fish for lab processing and analysis; the remainder were
quickly identified, counted, and released. The age classes were easily separated based on length
90
using a frequency histogram, and were confirmed with scale ages. Generally, Daphnia were
most important to the diet of Meziadin O. nerka, but Diacyclops, Eubosmina and insects also
played a significant role (Appendix 5).
Hydroacoustic assessments of Meziadin Lake should produce reasonable estimates of
juvenile sockeye abundance. Fish distribution on this lake, however, can lead to some
difficulties in estimating abundance. When large differences in densities from one part of the
lake to another occur, an increase in hydroacoustic sampling (number of transects) along with a
stratified design can help keep the 95% confidence limits in check. We used a two section
design, with five transects each, an increase of four transects over past surveys. Future surveys
may want to further increase the number of transects to seven in each of these sections, 14
transects in all, to further reduce confidence intervals. Surveys on this lake should expect to
have to deal with fish in the surface layers and have a strategy in place to sample and estimate
densities, whether this is with trawl nets, side looking acoustics, or some other means. If using a
trawl net, it would be best to have a smaller net available (3x3 m or 2x2 m) in order to sample
only the surface layer(s).
Moore Lake
Moore Lake is situated on Pitt Island on the north coast of British Columbia, about 16 km
west of Hartley Bay. It drains a short distance into Union Passage via Tsimtack Lake. Like most
coastal lakes, Moore is classified as stained. Moore Lake has a somewhat complicated
limnology due to a salt water layer occurring in the southern basin (Section 2) at about 20 m
depth where salinity increases significantly and dissolved oxygen starts to decrease. The
northern basin (Section 1) appears to consist of fresh water throughout the water column. We
surveyed this lake on September 7, 2008 with the Little Echo and the 2x2 m trawl. We found no
existing bathymetric chart for this lake, so we used our survey transect data along with addition
transects and soundings to produce our own chart (Fig. 3j).
Trawls indicated a large stickleback population and that the upper 10-12 meters of the
water column were predominately stickleback. O. nerka dominated in the deeper layers, below
16-20 meters, depending on lake section. Layers in between contained a mixture of the two
species. Because of the shallow stickleback layer we estimated stickleback contamination of
deeper trawls and adjusted the catch accordingly to calculate O. nerka/stickleback ratios. Most
stickleback were smaller than the O. nerka in this lake, and there were two size classes of
stickleback present; one centered around 52 mm, the other at 25 mm. This estimate was made
assuming the sounder was able to detect all stickleback present. However, there was some
concern that some or all of the smaller size class of stickleback were not detected at our analysis
thresholds. If this was the case, the O. nerka to stickleback ratio will change significantly,
leading to a higher O. nerka estimate. Our trawls caught 85 O. nerka, all age-0 fish, and 236
stickleback. Swedish gill nets caught an additional 20 stickleback (Appendix 2). Chaoborus
larvae were found to be present in the lake, but did not occur in sufficiently high densities to
91
significantly interfere with the hydroacoustic analyses. Both O. nerka and stickleback diet in
Moore lake includes major contributions from insects with minor contributions from the
zooplankters Eubosmina and Holopedium.
Hydroacoustic surveys of Moore Lake for juvenile sockeye abundance are definitely
possible. Extra trawling effort is needed estimate sockeye/stickleback proportions and some
research is needed to investigate the TS of small stickleback so researchers can better understand
how to calculate these proportions, and how they apply to the acoustic estimates. As well,
survey teams need to be aware of the meromictic nature of section 2 and to be prepared to deal
with Chaoborus should densities increase to the point where they interfere with the
hydroacoustic analysis. Transect 1 turned out to be quite shallow in depth (approx. 8 m max.)
and likely holds only stickleback; it could possibly be moved or eliminated from the survey
design.
Morice Lake
Morice Lake is in the interior Skeena region of British Columbia, about 65 km southwest
of Houston, B.C. Morice drains some 425 km to the ocean via the Morice, Bulkley and Skeena
rivers. We surveyed it on September 20, 2009 with the Night Echo and our 3x7 m trawl. We
had previously surveyed Morice in 2002 (Hume and MacLellan 2008) and we used the same
bathymetric chart and survey design. In Hume and MacLellan (2008) we classified Morice as
glacial and it is certainly glacially influenced, however, under the criteria developed for this
paper, it’s turbidity of 3.5 NTU (Table 1) falls below 5 NTU, which qualifies it as a clear lake.
Morice is a lake of extremes among our study lakes. It’s the largest and highest lake and
has the longest migration route for sockeye of all the other study lakes in this paper. It is likely
the least productive of the study lakes and ranks third for maximum depth, although the
bathymetry of Morice lake is poorly surveyed and the estimate of maximum depth may be
shallow.
During this survey we caught 22 O. nerka, mostly age-0 with a couple of age-1 fish, and
one whitefish. However all of these fish were captured at a single location, in an isolated bay at
the top end of Atna Bay (Transect 10) where, as in 2002, we found a typical layer of O. nerka.
The rest of Morice Lake is a different story, with pelagic fish few and far between, and scattered
throughout the water column. The vast majority of fish detected in the main lake were located
along the slope bottom, not typical of an O. nerka distribution. The fish caught at transect 10 can
hardly be considered representative of the whole lake. In 2002 we caught three fish in the main
lake, and they were smaller than most of the fish caught at transect 10. In 2002, we found O.
nerka at transect 10 to be feeding on Holopedium and insects. In 2009 they were feeding
primarily on Diacyclops and Bosmina (Appendix 5).
With no fish samples from the main lake, and so few hydroacoustic detections in the
pelagic zone, it is difficult to have much confidence in the 900 000 O. nerka estimate we arrived
92
at, so our reliability rating is “very low” (Appendix 3). It is clear, however, that O. nerka
densities in the main lake are extremely low. Until escapements to this lake system substantially
increase, a 1-2 night hydroacoustic survey to assess the abundance of juvenile sockeye will likely
fall short of producing reliable estimates. As a final note, our knowledge of the bathymetry of
Morice Lake is very poor and a full bathymetric survey of the lake should be conducted.
Namu Lake
Namu Lake is located on the central coast of British Columbia, a short distance east of
Namu B.C. The lake’s outlet stream drains for a few hundred metres into Fitz Hugh Sound. We
surveyed Namu, a stained lake, on September 15, 2006 using the Little Echo and the 2x2 m
trawl. Finding no existing bathymetric chart for Namu Lake, we drew up our own from survey
transects and additional soundings (Fig. 3k).
The trawl net caught 41 O. nerka, all age-0, and six stickleback. The stickleback were
relatively large with a mean length of 76 mm (Table 4); in most cases larger than the O. nerka,
which had a mean length of 55 mm (Table 3). Chaoborus larvae were present in this lake on
most transects in sufficient numbers to interfere with regular hydroacoustic analysis, so we
estimated O. nerka abundance at 177 000 fish using tracked target Chaoborus techniques as
outlined in MacLellan and Hume (2010). The diet of Namu O. nerka was varied, but Daphnia
was the main food item (Appendix 5).
Providing that Chaoborus densities do not increase to the point where distinguishing fish
targets is too difficult, future surveys for juvenile sockeye abundance should provide reasonable
estimates if the Chaoborus techniques mention above are used.
Red Bluff Lake
Red Bluff Lake is located on the east side of Pitt Island on the north coast of British
Columbia, about 22 km west and slightly north of Hartley Bay. It drains a short distance into
Grenville Channel, but the outlet creek has a barrier to anadromous fish. Like Batchellor Lake,
we surveyed this lake on July 23, 2006 with the Little Echo and the 2x2 m trawl, as part of the
Hanging lakes program, to evaluate existing fish stocks. We found no existing chart for this lake
so we produced one using our transect hydroacoustic data along with some additional soundings
(Fig. 3l). Red Bluff, like most coastal lakes, is stained.
Our midwater trawl caught 17 O. nerka (16 age-0, one age-1) and ten small larval fish.
The larval fish were considered too small to be detected by the sounder at our analysis threshold,
so their numbers were not applied to the hydroacoustic estimate. Swedish gill nets caught an
additional five age-1 O. nerka and two age-2+ O. nerka. Since adult sockeye do not have access
to the lake, these O. nerka must be kokanee, reproducing and rearing in Red Bluff Lake and its
93
tributaries. Other fishing gear caught threespine stickleback, sculpin and cutthroat trout. Age-0
O. nerka preferred Diaptomus in their diet, while age-1 O. nerka selected Bosmina and
Holopedium as well as Diaptomus.
Red bluff Lake is a good candidate for hydroacoustic assessment of O. nerka abundance.
The current population of kokanee is of very low density, but their distribution within the lake is
favorable to acoustic assessment and there is no reason planted sockeye fry would distribute
differently. That, along with few similar sized other species in the pelagic zone, should make an
O. nerka assessment fairly straightforward for this lake.
Tankeeah (lower) Lake
Lower Tankeeah Lake is situated on the Don Peninsula of British Columbia’s central
coast, about 21 km north west of Bella Bella. It is drained by the Tankeeah River a short
distance into Spiller Channel. Tankeeah Lower is made up of a complicated series of basins,
bays and islands and is relatively shallow with a maximum depth of 29 m. We surveyed this
lake on September 18, 2006 with the Little Echo and the 2x2 m trawl net. We drew a
bathymetric chart of the lake from our various soundings of the lake (Fig. 3m). Like most of the
coastal lakes we surveyed, this lake was classified as stained.
Of the 30 O. nerka captured during this survey, 29 were caught with the midwater trawl
and all were age-0 fish. In addition, three stickleback and one coho were caught by various
fishing gear. Chaoborus larvae were present in the lake and our O. nerka abundance estimate of
72 000 was arrived at by using tracked target and Chaoborus methods (MacLellan and Hume
2010). On most transects, Chaoborus densities were relatively low and did not pose much of a
problem. O. nerka of Tankeeah Lower Lake were feeding mainly on Bosmina and Holopedium
(Appendix 5), with some fish consuming Chaoborus larva as well.
As long as the Chaoborus methods above are employed and the Chaoborus population
remains at current levels, hydroacoustic assessments of this lake should produce reasonably good
estimates of O. nerka abundance.
Tankeeah (upper) Lake
Upper Tankeeah Lake is just north of Lower Tankeeah Lake and the two are connected
by a creek approximately 150 m in length. We surveyed this lake on September 19, 2006, the
next night after completing the lower lake survey, using the same gear. Again, we created our
own bathymetric chart from our hydroacoustic soundings (Fig. 3n). This lake is also classified
as stained.
We caught only four O. nerka, all age-0 fish, from this lake along with seven stickleback,
and all from midwater trawls. With such a low catch we pooled the trawl results and applied
94
them to the entire lake rather than on a section by section basis. Like Tankeeah Lower Lake,
Chaoborus were present in the upper lake and hydroacoustic data was handled in the same
manner to produce an O. Nerka estimate of 43 000 fish (Appendix 3). Diet differed in the upper
lake in that Diaptomus was the most important food item followed by Bosmina. It is important to
note however, that this is based on analysis of only three fish. (Appendix 5).
As with the lower lake, surveys of Upper Tankeeah should produce good estimates of O.
nerka abundance using Chaoborus methods. A higher trawl catch would be desirable, to better
estimate sockeye and stickleback ratios in each of the basins (sections 1 and 2), thus more
emphasis on trawling may be required.
Whalen Lake
Whalen is a relatively large lake (24 km long) located on Princess Royal Island, about 25
km south east of Hartley Bay, and in the north coast region of British Columbia. This stained
lake is drained by Whalen Creek, less than 1 km into Whale Channel. The drop from lake level
to sea level is over 100 m and there is a barrier on the creek preventing anadromous fish from
reaching the lake. We surveyed Whalen for the hanging lakes program on July 26, 2006 with the
Little Echo and our 2x2m trawl and used an existing bathymetric chart drawn up for the Ministry
of Environment, Lands and Parks in 1996 (FIDQ).
Only one fish, an age-1 O. nerka, was caught in 100 minutes of trawling. Gill nets
caught nine age-1 O. nerka along with several Dolly Varden trout and one coho salmon. We
found our gill nets were more successful catching O. nerka when deployed in the littoral zone of
the lake, suggesting the O. nerka, in this case kokanee, were utilizing the near shore areas of the
lake more than is typical of O. nerka populations. Dense layers of Chaoborus larvae were
present on most transects, dense enough to pose some difficulties for the analysis even using
tracked target Chaoborus techniques (MacLellan and Hume 2010). Many of the fish targets
detected in the pelagic zone were larger fish, most likely Dolly Varden and larger kokanee.
Some small fish, juvenile O. nerka sized, may be hidden amongst the Chaoborus signal, but they
are unlikely to be there in significant numbers, as indicated by the lack of catch in our midwater
trawls. With no evidence of other species in the small fish category in the pelagic zone, we
attributed all fish in that category to the juvenile kokanee estimate of 159 000 fish (Appendix 3).
It should be noted however, that if kokanee in this lake are shore oriented, we would have missed
a significant portion of the population, as our sampling design does not adequately sample the
near shore area. No diet workup was done for this lake due to the low trawl catch (one fish).
Hydroacoustic assessments of this lake have two challenges. The first is to separate fish
targets from Chaoborus targets in the pelagic zone. Chaoborus densities were fairly high for this
survey and any significant increase in these densities would certainly hamper analysis efforts.
The second involves the apparent preference of the existing kokanee population for near shore
habitat. Assessing littoral fish populations with acoustics is more difficult than pelagic
95
assessments, requiring more time and effort to adequately sample the population and analyze the
data. Why these kokanee prefer the near shore habitat is unclear. Zooplankton densities in the
pelagic zone, although on the low side (ranked 14th among our 20 study lakes), are not
excessively so (Appendix 6). Perhaps it is competition with the Chaoborus population that
forces them inshore. In any case, at this point it is unclear whether an introduced population of
juvenile sockeye would follow the norm and inhabit the pelagic zone of Whalen Lake or move
into the near shore habitat like the existing kokanee population.
96
Appendix 2. Record of trawls and sets completed during surveys of the study lakes.
Duration
Lake
Gear
Alastair
Trawl 2mx2m
97
Swedish gill net
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
13-Sep-09
14-Sep-09
23:40
20:29
1
1
15
15
1
8
1
8
Contin. rain
>50% cloud
Light breeze
Light air
14-Sep-09
20:59
1
30
14
14
>50% cloud
Light air
14-Sep-09
21:42
1
30
19
19
>50% cloud
Light air
14-Sep-09
22:23
1
35
30
30
>50% cloud
Light air
14-Sep-09
23:16
1
30
24
24
>50% cloud
Light air
15-Sep-09
15-Sep-09
0:48
1:26
2
2
20
20
1
6
1
6
Fog/haze
Fog/haze
Light air
Light air
15-Sep-09
2:01
2
20
12.5
12.5
Fog/haze
Light air
15-Sep-09
2:36
2
25
12.5
12.5
Fog/haze
Light air
15-Sep-09
3:15
2
20
18
18
Contin. rain
Light air
13-Sep-09
16:34
2
997
11
11
13-Sep-09
16:53
1
993
10.5
10.5
Taxa
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Age-1 O. nerka
Threespine stickleback
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-1 O. nerka
Threespine stickleback
Threespine stickleback
N
26
1
1
354
1
2
31
2
3
5
1
14
2
12
4
1
1
62
18
13
138
20
7
208
3
20
128
1
4
1
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Batchellor
Gear
Trawl 2mx2m
Swedish gill net
RIC gill net
98
Minnow trap
Beach seine
Bowser
Trawl 2mx2m
Date
Time
Section
(min)
Depth (m)
Start
End
14-Sep-09
20:40
2
445
7
7
14-Sep-09
20:55
2
440
14
14
21-Jul-06
21-Jul-06
20-Jul-06
20-Jul-06
21-Jul-06
21-Jul-06
20-Jul-06
22:53
23:16
18:27
19:05
10:45
11:00
15:27
1
1
1
1
1
1
1
15
30
976
948
1448
1405
1054
8
27
9
9
9
9
0
8
29
10.5
10.5
10.5
10.5
2
20-Jul-06
17:59
1
959
0
2
20-Jul-06
20-Jul-06
20-Jul-06
20-Jul-06
20-Jul-06
20-Jul-06
16:13
16:17
16:23
16:26
16:33
21:45
1
1
1
1
1
1
947
976
976
982
981
1.5
2
1.7
2
0.5
0
1.5
2
1.7
2
0.5
1
21-Jul-06
19:50
1
0
1
21-Jul-06
21-Jul-06
20:15
20:40
1
1
0
0
1
1
04-Sep-09
23:16
1
40
1
05-Sep-09
05-Sep-09
06-Sep-09
1:23
2:25
1:09
1
1
1
40
25
30
3
5
1
Conditions
Sky
Catch
Wind
Taxa
Age-0 O. nerka
Age-1 O. nerka
<10% cloud
<10% cloud
Light air
Light air
Dolly Varden
Cutthroat trout
Dolly Varden
Cutthroat trout
Dolly Varden
Dolly Varden
Dolly Varden
>50% cloud
Calm
1
10-50% cloud
Light air
3
5
1
10-50% cloud
10-50% cloud
Fog/haze
Light air
Light air
Light air
Dolly Varden
Dolly Varden
Cutthroat trout
Dolly Varden
Cutthroat trout
Dolly Varden
Cutthroat trout
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
N
1
1
0
0
0
0
1
0
0
37
1
19
2
2
1
0
1
1
6
2
11
1
2
0
1
1
2
0
3
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
99
Swedish gill net
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
06-Sep-09
1:13
2
30
3
3
Fog/haze
Light breeze
06-Sep-09
21:27
2
10
1
1
>50% cloud
Light air
06-Sep-09
21:59
2
7
1
1
>50% cloud
Light air
06-Sep-09
22:32
2
10
1.5
1.5
>50% cloud
Light air
06-Sep-09
23:03
2
17
1.5
1.5
>50% cloud
Light air
06-Sep-09
07-Sep-09
07-Sep-09
07-Sep-09
04-Sep-09
04-Sep-09
04-Sep-09
23:44
0:24
1:16
1:51
15:27
15:40
15:56
2
2
2
2
2
2
2
17
30
20
20
1217
1214
1209
1.5
1
1
3
5
2.5
3
1.5
1
1
3
5
2.5
3
>50% cloud
>50% cloud
>50% cloud
>50% cloud
Light air
Light air
Light air
Light air
04-Sep-09
05-Sep-09
16:28
15:22
2
2
1952
1294
3
1
3
1
05-Sep-09
05-Sep-09
05-Sep-09
06-Sep-09
11:58
12:08
12:35
13:29
2
2
2
2
1472
1492
1485
1151
2.5
3
0.5
0.5
2.5
3
0.5
0.5
06-Sep-09
13:40
2
1150
1
1
Taxa
Age-1 O. nerka
Age-2+ O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-2+ O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-0 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-1 O. nerka
Bull trout
Age-1 O. nerka
Age-2+ O. nerka
Coho salmon
Adult/jack sockeye
Age-2+ O. nerka
Age-1
Age-1
Sucker
Age-0
Age-1
O. nerka
O. nerka
O. nerka
O. nerka
N
3
1
3
3
1
2
10
4
2
4
5
2
1
1
0
0
6
1
1
0
5
6
1
1
1
0
1
3
1
1
2
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
100
Elbow
Gear
Trawl 2mx2m
Swedish gill net
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
Taxa
N
06-Sep-09
13:54
2
1157
0.5
0.5
Age-0 O. nerka
Age-1 O. nerka
Age-2+ O. nerka
Bull trout
Coho salmon
Adult/jack sockeye
3
24
6
2
2
1
06-Sep-09
14:03
2
1167
0.5
0.5
Age-0 O. nerka
Age-1 O. nerka
Age-2+ O. nerka
Bull trout
Coho salmon
3
20
8
1
2
20-Sep-07
21:34
1
18
15
15
<10% cloud
Light air
20-Sep-07
20-Sep-07
20-Sep-07
20-Sep-07
19-Sep-07
19-Sep-07
22:09
22:36
23:21
23:47
18:10
19:10
1
1
1
1
1
1
14
19
10
19
965
870
16
14
20
1
14
15
16
14
20
1
14
15
<10% cloud
10-50% cloud
>50% cloud
Intermit. rain
Light breeze
Light breeze
Light breeze
Light breeze
20-Sep-07
10:00
1
1350
15
15
20-Sep-07
10:25
1
1385
14
14
20-Sep-07
14:00
2
1290
2
2
Age-0 O. nerka
Coho salmon
Age-0 O. nerka
Age-0 O. nerka
Age-0 O. nerka
Sculpin
Age-0 O. nerka
Age-0 O. nerka
Age-2+ O. nerka
Age-0 O. nerka
Age-2+ O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-2+ O. nerka
Northern pikeminnow
2
1
5
2
2
5
2
1
3
1
1
3
1
1
3
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Fred Wright
Trawl 2mx2m
Swedish gill net
101
Keecha
Trawl 2mx2m
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
10-Sep-09
10-Sep-09
0:04
21:24
1
1
50
19
7
8
7
8
>50% cloud
Contin. rain
Gentle breeze
Calm
10-Sep-09
10-Sep-09
09-Sep-09
23:08
23:57
20:01
1
1
1
28
30
889
1
12
7
1
12
7
Contin. rain
Contin. rain
Light breeze
Light breeze
09-Sep-09
09-Sep-09
09-Sep-09
10-Sep-09
10-Sep-09
10-Sep-09
10-Sep-09
20:21
20:39
20:51
12:15
12:30
12:45
12:50
1
1
1
1
1
1
1
930
934
935
1152
1210
1208
1211
5
7
4
12
8
10
8
5
7
4
12
8
10
8
04-Sep-08
21:35
1
5
10
8
Intermit. rain
Light breeze
04-Sep-08
22:00
1
11
14
14
Intermit. rain
Light breeze
04-Sep-08
22:30
1
10
10
10
Intermit. rain
Light breeze
04-Sep-08
22:51
1
10
18
18
Intermit. rain
Light breeze
04-Sep-08
23:13
1
10
6
6
Intermit. rain
Light breeze
Taxa
Age-0 O. nerka
Sculpin
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Bull trout
Age-0 O. nerka
Threespine stickleback
Adult/jack sockeye
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Dolly Varden
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Threespine stickleback
N
0
2
2
0
0
1
3
0
1
0
0
0
0
1
1
11
5
1
66
2
2
1
16
1
10
29
1
1
21
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
102
Swedish gill net
Kimsquit
Trawl 2mx2m
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
04-Sep-08
23:41
1
10
1
1
Intermit. rain
Light breeze
05-Sep-08
22:41
4
5
11
11
<10% cloud
Calm
05-Sep-08
23:03
4
10
11
11
<10% cloud
Calm
05-Sep-08
23:27
3
10
11
10
<10% cloud
Calm
05-Sep-08
23:52
3
7
14
14
<10% cloud
Calm
06-Sep-08
0:15
4
7
14
14
<10% cloud
Calm
06-Sep-08
06-Sep-08
04-Sep-08
04-Sep-08
04-Sep-08
04-Sep-08
04-Sep-08
04-Sep-08
05-Sep-08
05-Sep-08
05-Sep-08
06-Sep-08
0:34
0:58
13:00
13:42
15:35
16:08
16:53
11:11
11:00
11:15
12:30
14:40
4
3
3
4
2
2
1
2
2
2
2
4
10
10
1308
1493
1167
1152
1120
1419
1423
1392
1323
1240
4
1
12
13
13
12
13
12
13
14
15
14
4
1
12
13
13
12
13
12
13
14
15
14
<10% cloud
<10% cloud
Calm
Calm
13-Sep-07
13-Sep-07
13-Sep-07
20:49
22:07
23:46
1
1
1
25
40
30
6
7
7
6
8
7
<10% cloud
<10% cloud
<10% cloud
Calm
Calm
Calm
14-Sep-07
0:43
1
20
20
20
<10% cloud
Light air
Taxa
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Prickly sculpin
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Age-0 O. nerka
Age-0 O. nerka
Age-0 O. nerka
Sculpin
Age-0 O. nerka
N
2
18
1
1
13
1
7
1
32
1
2
19
1
5
3
0
0
1
0
0
0
0
0
0
0
13
9
10
1
1
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Swedish gill net
Kitlope
Trawl 2mx2m
103
Swedish gill net
Koeye
Trawl 2mx2m
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
<10% cloud
Catch
Wind
14-Sep-07
12-Sep-07
12-Sep-07
1:27
21:16
21:50
1
1
1
15
954
940
1
5
7
1
5
7
13-Sep-07
13-Sep-07
19:04
19:16
1
1
916
883
7
5
7
5
15-Sep-07
21:43
1
45
3
3
Contin. rain
Light breeze
15-Sep-07
22:50
1
20
1.3
1.3
Contin. rain
Light breeze
16-Sep-07
22:03
1
55
2
2
10-50% cloud
Light breeze
15-Sep-07
17:42
1
1032
2
2
15-Sep-07
18:10
1
1013
3
3
16-Sep-07
16-Sep-07
16-Sep-07
12:00
10:54
11:05
1
1
1
1460
1456
1432
0
2
3
0
2
3
16-Sep-07
12:05
1
1555
0
0
12-Sep-06
21:07
1
25
10
10
<10% cloud
Light air
12-Sep-06
22:20
2
30
12
12
<10% cloud
Light air
Taxa
Light air
Age-0
Age-1
Age-0
Age-1
O. nerka
O. nerka
O. nerka
O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-1 O. nerka
Age-2+ O. nerka
Contin. rain
N
0
0
8
6
1
2
16
3
23
5
2
61
3
Threespine stickleback
Coho salmon
Age-0 O. nerka
Age-1 O. nerka
Coho salmon
2
5
9
1
0
0
1
1
4
5
1
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
14
1
56
Light breeze
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Kooryet
Gear
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
18:33
19:17
2
1
842
808
10
10
10
10
Trawl 2mx2m
02-Sep-08
02-Sep-08
20:46
21:30
3
3
16
10
10
13
10
13
<10% cloud
<10% cloud
Calm
Calm
02-Sep-08
02-Sep-08
21:52
22:28
3
2
10
12
7
11
7
11
<10% cloud
<10% cloud
Calm
Calm
02-Sep-08
22:54
1
30
14
14
<10% cloud
Calm
02-Sep-08
23:45
1
30
20
20
<10% cloud
Calm
02-Sep-08
02-Sep-08
0:43
0:49
1
2
20
15
8
1
8
1
<10% cloud
<10% cloud
Calm
Calm
01-Sep-08
01-Sep-08
01-Sep-08
01-Sep-08
01-Sep-08
02-Sep-08
02-Sep-08
02-Sep-08
02-Sep-08
02-Sep-08
15:25
16:51
17:05
17:21
18:05
10:55
11:09
11:25
10:04
10:24
2
1
1
2
3
1
1
2
3
2
1115
1029
1025
1020
945
1488
1521
1476
1501
1506
10.5
8
9
9
8
14
11
12
12
16
10.5
8
9
9
8
14
11
12
12
16
08-Sep-09
09-Sep-09
22:14
0:02
1
1
31
18
10
30
10
30
104
13-Sep-06
13-Sep-06
Small mesh gill net
Trawl 2mx2m
Catch
Wind
Swedish gill net
Swedish gill net
Kwinageese
Date
Taxa
N
0
0
Age-0 O. nerka
Age-0 O. nerka
Threespine stickleback
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-1 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Contin. rain
Contin. rain
Light air
Light air
Coho salmon
Age-1 O. nerka
11
7
1
3
2
3
39
1
27
6
1
4
5
0
0
0
1
0
0
0
0
0
0
2
1
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Swedish gill net
105
Lonesome
Trawl 2mx2m
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
Taxa
N
09-Sep-09
09-Sep-09
0:46
1:27
1
1
30
30
24
6
24
6
Contin. rain
Contin. rain
Light air
Light air
09-Sep-09
07-Sep-09
07-Sep-09
07-Sep-09
2:10
20:06
23:05
21:01
1
1
1
1
30
749
744
734
1
5
6
6
1
5
6
6
Contin. rain
Light air
07-Sep-09
21:31
1
779
5
5
08-Sep-09
08-Sep-09
08-Sep-09
08-Sep-09
8:50
11:18
11:35
11:55
1
1
1
1
1498
1361
1353
1340
10
8
7
7
10
8
7
7
08-Sep-07
09-Sep-07
23:25
0:08
1
1
20
20
15
30
16
30
<10% cloud
<10% cloud
Light breeze
Light breeze
Age-0 O. nerka
Age-0 O. nerka
prickly sculpin
9
1
3
09-Sep-07
0:53
1
20
24
24
<10% cloud
Light breeze
09-Sep-07
1:30
1
20
19
19
<10% cloud
Calm
11-Sep-07
20:50
1
20
16
16
<10% cloud
Gentle breeze
11-Sep-07
11-Sep-07
11-Sep-07
21:31
22:17
22:47
1
1
1
25
15
20
17
16
1
17
19
1
<10% cloud
<10% cloud
<10% cloud
Gentle breeze
Gentle breeze
Gentle breeze
Age-0 O. nerka
Age-1 O. nerka
Sculpin
Age-0 O. nerka
Age-1 O. nerka
Sculpin
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-0 O. nerka
3
1
2
3
1
1
14
1
18
15
0
Age-0 O. nerka
Coho salmon
Rainbow trout
Age-2+ O. nerka
redside shiner
Lake chub
Redside shiner
Lake chub
Redside shiner
0
1
2
0
1
1
13
4
49
1
0
1
0
0
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Swedish gill net
Meziadin
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
08-Sep-07
15:38
1
1228
15
15
<10% cloud
08-Sep-07
11-Sep-07
16:15
12:51
1
1
1216
1059
15
17
15
17
<10% cloud
0
1
Catch
Wind
11-Sep-07
Trawl 3mx7m
17-Sep-09
21:47
2
20
10
10
Contin. rain
Light breeze
17-Sep-09
22:53
2
15
21
21
Contin. rain
Light breeze
18-Sep-09
0:03
2
15
3.5
3.5
Contin. rain
Light breeze
18-Sep-09
22:19
1
20
3.5
3.5
Contin. rain
Light breeze
18-Sep-09
23:24
1
20
11
11
>50% cloud
Light breeze
18-Sep-09
0:21
1
10
19
19
>50% cloud
Light breeze
07-Sep-08
22:06
2
20
14
14
Intermit. rain
Light air
07-Sep-08
07-Sep-08
22:52
23:25
2
2
20
17
9
18
9
20
>50% cloud
>50% cloud
Light air
Light air
07-Sep-08
23:53
2
15
14
12
>50% cloud
Light air
08-Sep-08
20:45
1
10
13
13
<10% cloud
Gentle breeze
Trawl 2mx2m
Taxa
Age-0 O. nerka
Age-1 O. nerka
Rainbow trout
Age-0 O. nerka
Age-0 O. nerka
Age-2+ O. nerka
Cutthroat trout
Northern pikeminnow
Prickly sculpin
Dip net
106
Moore
Date
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Whitefish
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Threespine stickleback
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
N
2
1
1
2
7
3
1
1
1
281
27
208
144
126
2
11
1
70
146
5
21
17
1
13
8
2
13
4
9
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Swedish gill net
107
Small mesh gill net
Morice
Namu
Trawl 3mx7m
Trawl 2mx2m
Swedish gill net
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
08-Sep-08
21:15
1
22
17
17
<10% cloud
Moderate breeze
08-Sep-08
22:08
1
16
22
26
<10% cloud
Gentle breeze
08-Sep-08
08-Sep-08
07-Sep-08
07-Sep-08
07-Sep-08
08-Sep-08
08-Sep-08
08-Sep-08
07-Sep-08
07-Sep-08
08-Sep-08
08-Sep-08
22:43
23:21
13:18
14:28
15:24
13:30
13:40
14:15
13:29
15:50
13:11
13:55
1
1
2
1
1
1
1
1
2
1
2
1
15
20
1413
1320
1354
1214
1217
1193
1409
1320
1224
1197
9
1
10
13
5
20
16
7
13
12
13
18
9
1
10
13
5
20
16
7
13
12
13
18
<10% cloud
<10% cloud
Gentle breeze
Gentle breeze
22-Sep-09
23:35
3
15
17
17
<10% cloud
Light air
23-Sep-09
23-Sep-09
0:21
1:07
3
3
15
25
24
18
24
18
<10% cloud
<10% cloud
Light air
Light air
15-Sep-06
20:36
2
13
8
8
<10% cloud
Light breeze
15-Sep-06
15-Sep-06
21:51
23:48
2
1
15
35
9
11
9
10
<10% cloud
10-50% cloud
Light air
Light air
15-Sep-06
15-Sep-06
19:05
19:25
1
2
930
1129
7
7
8.5
8.5
Taxa
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
N
45
25
9
13
5
111
46
3
0
7
0
0
10
0
0
0
0
Age-0 O. nerka
Age-1 O. nerka
whitefish
Age-0 O. nerka
Age-0 O. nerka
6
2
1
2
12
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-0 O. nerka
Threespine stickleback
6
2
8
27
4
0
2
Age-0 O. nerka
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Red Bluff
Trawl 2mx2m
108
Swedish gill net
RIC gill net
Minnow trap
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
23-Jul-06
24-Jul-06
24-Jul-06
23:05
1:10
1:42
3
2
2
30
10
30
10
12
12
10
12
12
<10% cloud
<10% cloud
<10% cloud
Calm
Calm
Calm
24-Jul-06
22:47
2
30
12
12
Intermit. rain
Light breeze
24-Jul-06
23:39
2
20
14
14
Intermit. rain
Light air
25-Jul-06
0:58
1
10
10
12
Intermit. rain
Light air
25-Jul-06
23-Jul-06
1:25
20:34
1
1
8
909
10
10
10
11.5
>50% cloud
Light air
23-Jul-06
24-Jul-06
23-Jul-06
23-Jul-06
24-Jul-06
24-Jul-06
24-Jul-06
23-Jul-06
23-Jul-06
23-Jul-06
23-Jul-06
23-Jul-06
24-Jul-06
20:57
14:58
12:20
13:38
14:31
16:52
20:15
13:45
13:55
14:03
14:12
14:20
14:22
2
2
1
1
2
2
2
1
1
1
1
2
2
1073
1167
415
386
331
1013
760
1331
1330
1331
1332
1365
1133
10
10
0
0
0
0
0
1
2
0.5
1.5
1
2
11.5
11.5
2
2
2
2
2
1
2
0.5
1.5
1
2
24-Jul-06
24-Jul-06
14:35
14:46
2
2
1130
120
2.5
0
2.5
2
Taxa
Age-0 O. nerka
Age-0 O. nerka
Larval fish
Age-0 O. nerka
Larval fish
Age-0 O. nerka
Larval fish
Age-0 O. nerka
Age-1 O. nerka
Age-0 O. nerka
Age-1 O. nerka
Age-2+ O. nerka
Cutthroat trout
Cutthroat trout
Cutthroat trout
Cutthroat trout
Cutthroat trout
Cutthroat trout
Cutthroat trout
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Threespine stickleback
Sculpin
Cutthroat trout
N
0
3
4
5
2
3
4
2
2
1
1
5
2
2
1
0
6
7
5
5
3
15
6
27
37
14
7
2
0
1
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Dip net
Beach seine
Tankeeah (lower)
Trawl 2mx2m
109
Swedish gill net
Tankeeah (upper)
Trawl 2mx2m
Swedish gill net
Whalen
Trawl 2mx2m
Date
Time
Section
(min)
Depth (m)
Start
End
Conditions
Sky
Catch
Wind
24-Jul-06
24-Jul-06
16:51
17:00
2
2
1074
1058
1
1
1
1
24-Jul-06
25-Jul-06
25-Jul-06
17:04
8:00
15:00
2
2
2
1046
1
0.5
0
1
0.5
1.5
18-Sep-06
18-Sep-06
20:43
21:05
3
3
7
10
7
7
7
7
>50% cloud
>50% cloud
Light air
Light air
18-Sep-06
18-Sep-06
21:31
23:25
3
2
13
7
9
6
7
7
>50% cloud
>50% cloud
Light air
Light air
18-Sep-06
18-Sep-06
18-Sep-06
0:07
19:15
19:35
1
2
3
8
920
910
8
4
5
6
5.5
6.5
10-50% cloud
Light air
19-Sep-06
19-Sep-06
21:52
22:04
1
1
4
7
8
8.5
5
8.5
Contin. rain
Contin. rain
Light air
Light air
19-Sep-06
19-Sep-06
19-Sep-06
23:11
18:55
19:10
2
1
2
9
830
780
7.5
7
7
7.5
8.5
8.5
Contin. rain
Light air
27-Jul-06
27-Jul-06
27-Jul-06
28-Jul-06
0:06
2:06
22:23
0:05
1
1
2
2
30
30
20
20
11
12
10
12
11
15
10
12
>50% cloud
>50% cloud
>50% cloud
<10% cloud
Light breeze
Light breeze
Light air
Light air
Taxa
Threespine stickleback
Threespine stickleback
Sculpin
Sculpin
Threespine stickleback
Sculpin
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Age-0 O. nerka
Threespine stickleback
Age-0 O. nerka
Threespine stickleback
Coho salmon
Age-0 O. nerka
Age-0 O. nerka
Threespine stickleback
Threespine stickleback
Age-1 O. nerka
N
4
12
2
0
1
59
6
0
5
1
14
10
1
0
0
1
1
1
1
3
6
1
0
0
0
1
0
0
Appendix 2. Record of trawls and sets completed during surveys of the study lakes (Continued).
Duration
Lake
Gear
Swedish gill net
RIC gill net
Minnow trap
Date
Time
Section
(min)
Depth (m)
Start
End
110
26-Jul-06
26-Jul-06
27-Jul-06
27-Jul-06
27-Jul-06
26-Jul-06
12:38
12:53
11:05
17:50
11:00
10:58
1
1
1
1
2
1
1344
1342
1400
965
1405
1547
8.5
8.5
8.5
0
8.5
0
10
10
10
1.5
10
2
26-Jul-06
11:31
1
1494
0
2
27-Jul-06
27-Jul-06
26-Jul-06
26-Jul-06
26-Jul-06
26-Jul-06
26-Jul-06
27-Jul-06
27-Jul-06
27-Jul-06
12:00
12:50
11:03
11:06
11:09
11:35
11:37
12:08
12:10
12:15
2
1
1
1
1
1
1
1
1
1
1295
1265
1502
1504
1506
1515
1523
222
215
205
0
0
1.5
0.5
2
1
1
0.5
0.5
1
2
2
1.5
0.5
2
1
1
0.5
0.5
1
Conditions
Sky
Catch
Wind
Taxa
Age-1 O. nerka
Coho salmon
Dolly Varden
Age-1 O. nerka
Dolly Varden
Dolly Varden
Age-1 O. nerka
Dolly Varden
Dolly Varden
Dolly Varden
Dolly Varden
Dolly Varden
N
0
1
0
0
0
1
12
6
2
5
2
1
3
1
3
1
0
0
0
Appendix 3. Hydroacoustic estimates of pelagic fish populations.
Juvenile O. nerka
Lake
Analysis
Other Small Fish
N
(N/ha)
95%
CI
31
31
32
Large Fish
(N/ha)
95%
CI
Reliability
of
Estimate
62,945
59,409
58,666
92
87
86
44
41
40
Medium
Medium
Medium
14,800
26
71
Medium
822
0.2
143
Very low
(N/ha)
95%
CI
N
3,985,014
3,973,694
4,004,647
5,836
5,819
5,865
36
37
37
86,154
150
50
N
111
Alastair
Integration
Single targets
Tracked targets
a
371,654
387,025
412,185
544
567
604
Batchelor
Tracked targets CHA
a
-
-
Bowser
Tracked targets/trawl
a
131,668
39
13
-
-
Elbow
Integration
Single targets
Tracked targets
16,194
15,438
15,993
155
147
153
58
74
87
1,466
1,397
1,448
14
13
14
58
74
87
10,018
10,128
10,453
96
97
100
64
69
71
Medium
Medium
Medium
a
Fred Wright
Tracked targets
a
45,071
118
60
232,958
610
108
2,837
7
92
Low
Keecha
Tracked targets CHA
a
231,302
727
29
145,443
457
22
10,708
34
57
Medium
Kimsquit
Integration
Single targets
Tracked targets
a
120,654
122,083
122,407
761
770
772
32
34
27
3,603
3,646
3,656
23
23
23
32
34
27
21,909
22,948
23,681
138
145
149
40
49
46
High
High
High
Kitlope
Integration/trawl
Single targets/trawl
Tracked targets/trawl
288,913
289,579
269,217
295
296
275
35
30
28
5,296
5,308
4,935
5
5
5
35
30
28
8,474
10,135
9,125
9
10
9
184
187
173
Low
Low
Low
a
Appendix 3. Hydroacoustic estimates of pelagic fish populations (Continued).
Juvenile O. nerka
Lake
Analysis
Other Small Fish
N
(N/ha)
95%
CI
N
Large Fish
(N/ha)
95%
CI
N
(N/ha)
95%
CI
Reliability
of
Estimate
112
Koeye
Tracked targets CHA
a
484,180
1,063
33
9,991
22
56
26,258
58
61
Medium
Kooryet
Integration
Single targets
Tracked targets
a
118,610
135,222
169,348
241
275
344
17
18
18
265,720
224,696
275,399
540
457
560
35
26
31
7,752
8,738
11,088
16
18
23
42
48
46
High
High
High
Kwinageese
Single targets
Tracked targets
6,500
5,884
25
23
98
94
13,019
11,786
50
46
98
94
4,298
3,588
17
14
123
115
Low
Low
6,150
6,413
8,229
24
25
32
48
49
53
High
High
High
a
Lonesome
Integration
Single targets
Tracked targets
a
129,548
132,840
170,949
496
508
654
33
37
39
-
-
Meziadin
Integration
Single targets
Tracked targets
a
9,197,825
10,414,610
8,897,612
2,613
2,959
2,528
53
53
53
9,938
9,841
4,829
3
3
1
144
128
117
1,039,277
1,120,918
1,116,064
295
319
317
69
70
72
Medium
Medium
Medium
Moore
Integration
Single targets
Tracked targets
a
64,135
66,424
83,717
229
238
300
56
63
61
596,603
585,883
603,565
2,134
2,096
2,159
48
52
52
1,476
1,289
1,611
5
5
6
163
161
160
Medium
Medium
Medium
Appendix 3. Hydroacoustic estimates of pelagic fish populations (Continued).
Juvenile O. nerka
Lake
Morice
Analysis
Integration
Single targets
Tracked targets
Tracked targets CHA
Red Bluff
Integration
Single targets
Tracked targets
113
Namu
a
a
a
Other Small Fish
Large Fish
(N/ha)
N
(N/ha)
Reliability
of
Estimate
N
(N/ha)
475,798
620,339
901,974
49
64
93
44
32
36
21,379
27,873
40,528
2
3
4
44
32
36
34,131
32,330
40,178
4
3
4
74
59
57
Very low
Very low
Very low
177,157
548
34
25,955
80
35
27,993
87
36
Medium
124,908
130,695
131,756
158
165
166
89
81
80
-
-
30,511
36,701
36,828
39
46
46
66
65
69
High
High
High
N
95%
CI
95%
CI
95%
CI
Tankeeah (lower)
Tracked targets CHA
a
72,270
479
39
5,205
35
41
21,243
141
45
Medium
Tankeeah (upper)
Tracked targets CHA
a
42,569
330
37
74,379
577
37
3,345
26
116
Medium
158,839
74
Whalen
Tracked targets CHA a
a
Prefered/Reported analysis method
CHA - tracked target anaysis with chaoborus methods employed
36
-
-
215,149
101
19
Medium
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa.
Catch
Lake/Date
Alastair
Gear
Trawl (2mx2m)
13/09/2009
Swed gill net
114
Batchellor
Beach sceine
20/07/2006
Formalin
Taxa
n
n
mean
O. nerka age-0
34
34
1.74
95CI
SD
Fork length (mm)
min
0.18
0.52
0.61
max
2.76
n
34
mean
95CI
SD
min
max
54
2.2
6.2
37
64
Ethanol 85%
O. nerka age-0
13
13
1.78
0.18
0.3
1.16
2.14
13
59
1.8
3
52
62
Formalin
O. nerka age-1
42
42
4.76
0.31
1
2.21
6.61
42
76
1.6
5.2
63
86
Ethanol 85%
O. nerka age-1
7
7
4.71
0.32
0.34
4.15
5.23
7
79
1.4
1.5
77
81
Formalin
Stickleback
353
353
1.45
0.07
0.7
0.02
3.39
353
50
1
9.8
14
71
Live
Stickleback
629
0
58
58
83
Formalin
O. nerka age-0
1
1
0
2.17
2.17
2.17
1
58
Formalin
O. nerka age-1
2
2
6
9.02
1
5.29
6.71
2
80
38.1
4.2
77
Formalin
Stickleback
4
4
2.28
1.27
0.8
1.16
3.05
4
60
13.1
8.2
49
69
Live
Stickleback
1
0
1
40
40
40
Cutthroat trout
19
19
3.45
2.3
4.77
0.25
13.96
19
51
28
100
6.36
4.76
1.92
4.5
8.33
Formalin
13
27.1
Formalin
Dolly Varden
3
3
3
79
18.8
7.5
72
87
Minnow trap(s)
Live
Dolly Varden
5
0
5
121
28.1
22.7
92
145
RIC gill net
Live
Cutthroat trout
56
0
56
242
10
37.5
113
325
Live
Dolly Varden
3
0
3
152
59.6
24
125
170
Live
Dolly Varden
1
0
1
222
222
222
67
Swed gill net
Bowser
Fish State
Weight (gm)
Trawl (2mx2m)
04/09/2009
Swed gill net
Formalin
O. nerka age-0
12
12
1.87
0.55
0.87
0.7
3.53
12
53
5.5
8.6
38
Ethanol 85%
O. nerka age-0
13
13
1.36
0.32
0.52
0.41
2.1
13
52
4.4
7.3
37
61
Formalin
O. nerka age-1
14
14
4.36
0.41
0.71
3.08
5.63
14
71
2.2
3.7
64
76
Ethanol 85%
O. nerka age-1
7
7
3.02
1.19
1.29
1.09
4.79
7
68
9.8
10.6
50
81
Formalin
O. nerka age-2+
1
1
11.05
11.05
11.05
1
95
95
95
Ethanol 85%
O. nerka age-2+
2
2
6.02
9.21
1.03
5.29
6.74
2
85
25.4
2.8
83
87
Formalin
O. nerka age-0
7
6
2.2
0.22
0.22
1.98
2.44
6
58
3.4
3.4
54
63
Formalin
O. nerka age-1
62
62
4.69
0.29
1.13
2.33
9.16
62
74
1.4
5.4
59
90
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa (Continued).
Catch
Lake/Date
Gear
Fish State
Formalin
Elbow
Trawl (2mx2m)
115
Trawl (2mx2m)
09/09/2009
Swed gill net
04/09/2008
Trawl (2mx2m)
mean
O. nerka age-2+
21
21
11.14
23.49
Bull trout
1
1
3
0
95CI
2.19
SD
4.81
Fork length (mm)
min
max
n
5.5
21.25
23.49
23.49
Formalin
Sucker
1
1
24.15
Formalin
Coho salmon
5
5
14.37
sockeyeb
2
0
O. nerka age-0
11
11
5.66
1.65
2.46
2.49
Sculpin
5
5
0.1
0.12
0.1
0.04
Coho salmon
1
1
9.92
Formalin
O. nerka age-0
3
3
9.22
3.95
Ethanol 85%
O. nerka age-0
4
4
7.34
5.94
Ethanol 85%
O. nerka age-1
1
1
26.15
Formalin
O. nerka age-2+
3
3
95.93
37.83
Ethanol 85%
Ethanol 85%
2.74
mean
95CI
SD
min
max
21
96
5.6
12.2
79
124
1
121
121
121
3
347
138
55.6
290
401
24.15
24.15
1
120
120
120
12.57
18.09
5
103
6.2
5
98
110
2
516
50.8
5.7
512
520
11.96
11
80
6.3
9.4
64
102
0.27
5
21
7.7
6.2
15
31
9.92
9.92
1
99
99
99
1.59
7.57
10.74
3
88
13.1
5.3
82
92
3.73
3.8
12.59
4
86
22.1
13.9
72
105
26.15
26.15
1
134
134
134
15.23
78.68
107.53
3
192
26.6
10.7
180
199
2.21
O. nerka age-2+
2
2
82.81
146.82
16.34
71.25
94.36
2
198
38.1
4.2
195
201
Formalin
NPMa
3
3
139.27
45.81
18.44
123.8
159.68
3
223
32.3
13
210
236
70
Formalin
O. nerka age-0
2
2
3.51
11.75
1.31
2.58
4.43
2
65
63.5
7.1
60
Formalin
Sculpin
2
2
0.08
0.44
0.05
0.04
0.11
2
17
31.8
3.5
14
19
Formalin
O. nerka age-0
2
2
7.06
10.42
1.16
6.24
7.88
2
84
50.8
5.7
80
88
Formalin
O. nerka age-1
4
4
14.99
17.04
10.71
9.23
31.05
4
106
32.7
20.5
Bull trout
1
0
1
555
Live
Keecha
n
Bull trout
Ethanol 85%
Fred Wright
n
Live
Formalin
Swed gill net
Taxa
Formalin
Live
19/09/2007
Weight (gm)
94
137
555
555
Formalin
O. nerka age-0
172
172
1.96
0.11
0.7
0.79
3.62
172
55
1
6.8
41
69
Ethanol 85%
O. nerka age-0
20
20
1.89
0.25
0.53
0.81
2.63
20
59
2.3
5
48
67
Ethanol 95%
O. nerka age-0
5
5
1.81
0.75
0.6
1.21
2.69
5
60
7.1
5.7
54
67
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa (Continued).
Catch
Lake/Date
Gear
Fish State
Formalin
O. nerka age-1
Ethanol 95%
Kimsquit
12/09/2007
Trawl (2mx2m)
116
Swed gill net
Kitlope
Trawl (2mx2m)
15/09/2007
Swed gill net
n
n
4
mean
4
5.62
95CI
SD
1.67
1.05
0.22
0.92
Fork length (mm)
min
max
n
mean
95CI
SD
min
max
4
79
7.2
4.5
74
85
80
80
2.1
8.6
48
78
4.51
7.03
4.15
4.15
1
80
0.93
4.41
69
63
O. nerka age-1
1
1
4.15
Formalin
Stickleback
69
69
2.25
Formalin
Prickly sculpin
1
1
1.98
1.98
1.98
1
62
62
62
Formalin
Dolly Varden
1
1
27.78
27.78
27.78
1
140
140
140
1
380
380
380
2.02
2.02
1
66
66
66
sockeyeb
1
0
Formalin
Stickleback
1
1
2.02
Live
Swed gill net
Taxa
Weight (gm)
Formalin
O. nerka age-0
13
13
1.33
0.55
0.91
0.28
2.97
13
45
6.4
10.6
29
61
Ethanol 85%
O. nerka age-0
20
20
1.19
0.42
0.91
0.19
2.52
20
48
6.1
13.1
31
64
Ethanol 85%
Sculpin
1
1
0.33
0.33
0.33
1
34
Formalin
O. nerka age-0
9
8
4.09
0.77
0.95
2.08
5.04
8
69
4.8
Formalin
O. nerka age-1
8
8
6.96
2.05
2.45
4.37
11.76
8
82
34
34
5.8
56
74
7.6
9.1
70
97
Formalin
O. nerka age-0
75
75
1.38
0.11
0.46
0.71
2.93
75
49
1.3
5.5
37
65
Ethanol 85%
O. nerka age-0
25
25
1.1
0.13
0.32
0.64
1.93
25
51
1.9
4.6
42
61
Formalin
O. nerka age-1
5
5
4.6
1.13
0.91
3.93
6.16
5
73
7.9
6.4
68
83
Live
O. nerka age-1
1
0
1
90
Ethanol 85%
O. nerka age-1
5
5
5
70
5.8
3.44
0.88
0.71
2.71
4.2
4.7
90
90
66
77
Formalin
Stickleback
2
2
0.96
4.38
0.49
0.61
1.3
2
45
69.9
7.8
39
50
Formalin
O. nerka age-0
6
6
2.42
0.55
0.52
1.92
3.39
6
59
3.7
3.5
55
65
Formalin
O. nerka age-1
17
15
5.04
0.57
1.03
4.09
7.33
17
76
2.9
5.6
71
89
Live
O. nerka age-1
2
0
2
93
31.8
3.5
Formalin
O. nerka age-2+
1
1
14.68
14.68
1
107
1.14
1.14
1
46
3.68
6.2
2
71
14.68
Formalin
Stickleback
1
1
1.14
Formalin
Coho salmon
2
2
4.94
16.01
1.78
76.2
8.5
90
95
107
107
46
46
65
77
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa (Continued).
Catch
Lake/Date
Koeye
Gear
Trawl (2mx2m)
12/09/2006
Kooryet
Trawl (2mx2m)
01/09/2008
Swed gill net
117
Kwinageese
Trawl (2mx2m)
07/09/2009
Swed gill net
Lonesome
08/09/2007
Trawl (2mx2m)
Fish State
Weight (gm)
mean
95CI
SD
Fork length (mm)
Taxa
n
n
min
max
Formalin
O. nerka age-0
36
36
1.79
0.23
0.69
0.4
Ethanol 85%
O. nerka age-0
34
34
1.44
0.13
0.37
Ethanol 85%
Stickleback
1
1
0.27
n
mean
95CI
SD
min
max
3.44
36
52
2.7
7.9
33
66
0.75
2.2
34
55
1.7
5
44
63
0.27
0.27
1
31
31
31
Formalin
O. nerka age-0
35
35
2.34
0.41
1.19
0.85
7.23
35
57
2.9
8.5
42
86
Ethanol 85%
O. nerka age-0
26
26
1.91
0.26
0.65
0.94
3.33
26
59
2.5
6.3
47
71
Ethanol 95%
O. nerka age-0
4
4
1.72
1.14
0.72
11.4
7.1
50
66
Ethanol 85%
O. nerka age-1
1
1
2.54
67
67
Formalin
Stickleback
44
44
3.53
Formalin
Stickleback
1
1
4.07
Formalin
O. nerka age-0
1
1
0.72
Formalin
O. nerka age-1
1
1
14.11
Formalin
Coho salmon
4
4
0.36
Formalin
O. nerka age-2+
1
1
29.13
Formalin
Redside shiner
62
55
7.15
0.26
0.4
0.44
0.87
0.25
1.65
1
2.56
4
58
2.54
2.54
1
67
0.64
4.55
44
73
4.07
4.07
1
77
0.72
0.72
1
38
38
38
14.11
14.11
1
101
101
101
2.5
10.2
8.3
81
77
77
0.11
0.65
4
31
29.13
29.13
1
130
3.28
11.06
55
78
1
80
80
80
27.05
27.05
1
129
129
129
1.5
6.4
39
5.7
24
38
130
130
61
90
Live
Redside shiner
1
0
Formalin
Rainbow trout
1
1
27.05
Formalin
Lake chub
5
5
18.52
7.99
6.43
7.86
24.77
5
115
19.5
15.7
88
128
Formalin
O. nerka age-0
34
34
1.89
0.24
0.7
1.06
3.95
34
54
2.1
6
45
70
Ethanol 85%
O. nerka age-0
29
29
1.83
0.42
1.09
0.85
6.06
29
58
3.2
8.4
48
87
Ethanol 85%
O. nerka age-1
3
3
10.04
5.92
2.39
7.65
12.42
3
101
19.9
8
93
109
1.52
0.17
57.2
6.4
Formalin
Sculpin
2
2
0.31
Ethanol 85%
Sculpin
1
1
0.16
Prickly sculpin
3
3
4.25
Formalin
5.96
2.4
0.19
0.43
2
31
0.16
0.16
1
27
1.93
6.72
3
66
28.6
11.5
26
35
27
27
54
77
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa (Continued).
Catch
Lake/Date
Gear
Dip net
Swed gill net
118
Meziadin
Trawl (3mx7m)
17/09/2009
Fish State
Moore
Trawl (2mx2m)
Swed gill net
n
n
mean
95CI
SD
Fork length (mm)
min
max
n
mean
95CI
SD
min
max
Formalin
NPMa
1
1
96.33
96.33
96.33
1
193
193
193
Formalin
Prickly sculpin
1
1
41.42
41.42
41.42
1
135
135
135
Formalin
O. nerka age-0
4
3
2.93
1.76
0.96
2.18
4.01
3
62
11.1
6
56
68
Ethanol 85%
O. nerka age-0
7
6
3.19
0.22
0.22
2.93
3.43
6
70
2.1
2.1
67
73
Formalin
O. nerka age-1
1
1
25.63
25.63
25.63
1
127
127
127
Formalin
O. nerka age-2+
2
2
203.56
124.75
282.36
2
238
193
282
Live
O. nerka age-2+
1
0
1
212
212
212
Live
Rainbow trout
1
0
1
331
331
331
Live
Cutthroat trout
1
0
1
265
265
265
Formalin
O. nerka age-0
382
381
54
30
88
Live
O. nerka age-0
259
0
Ethanol 85%
O. nerka age-0
60
Formalin
O. nerka age-1
99
Live
O. nerka age-1
205
0
Ethanol 85%
O. nerka age-1
36
Whitefish
1
Formalin
07/09/2008
Taxa
Weight (gm)
1001.3
111.45
565.4
0.8
62.9
1.84
0.09
0.87
0.28
7.85
381
8.4
60
1.73
0.15
0.58
0.46
2.9
60
57
1.7
6.6
39
68
99
9.53
0.5
2.5
4.3
20.36
99
94
1.5
7.6
73
121
36
8.69
0.87
2.57
3.63
15.56
36
96
3.2
9.5
72
115
1
22.5
22.5
22.5
1
125
125
125
0
0
Formalin
O. nerka age-0
62
62
2.75
0.11
0.43
1.46
3.37
62
62
0.9
3.4
50
67
Ethanol 85%
O. nerka age-0
20
20
2.32
0.22
0.48
1.07
2.97
20
63
2.2
4.7
49
68
Ethanol 95%
O. nerka age-0
3
3
2.26
0.55
0.22
2.07
2.5
3
64
4.3
1.7
63
66
Formalin
Stickleback
231
231
0.77
0.09
0.7
0.06
2.48
231
38
1.8
14
18
63
Ethanol 85%
Stickleback
5
5
1.1
0.79
0.63
0.07
1.61
5
47
19
15.3
20
57
Formalin
Stickleback
20
20
1.4
0.16
0.34
0.9
2.5
20
52
1.6
3.3
48
62
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa (Continued).
Catch
Lake/Date
Morice
Gear
Trawl (3mx7m)
22/09/2009
Namu
Trawl (2mx2m)
15/09/2006
119
Red Bluff
Fish State
Weight (gm)
Taxa
n
n
mean
95CI
SD
Fork length (mm)
min
max
n
mean
95CI
SD
min
max
Formalin
O. nerka age-0
20
20
4.12
0.94
2
1.04
7.58
20
70
5.5
11.8
46
87
Formalin
O. nerka age-1
2
2
13.06
7.24
0.81
12.49
13.63
2
102
38.1
4.2
99
105
Formalin
Whitefish
1
1
6.47
6.47
6.47
1
89
89
89
Formalin
O. nerka age-0
21
21
2.12
0.35
0.77
0.57
3.66
21
54
7.4
35
66
Ethanol 85%
71
3.4
O. nerka age-0
20
20
1.9
0.44
0.93
0.53
3.63
20
57
4.2
8.9
41
Formalin
Stickleback
6
6
4.45
2.19
2.08
1.48
6.19
6
76
13.6
12.9
57
89
Swed gill net
Formalin
O. nerka age-0
2
1
2.34
2.34
2.34
1
59
59
59
Trawl (2mx2m)
Ethanol 85%
O. nerka age-0
16
16
0.4
0.13
0.99
16
38
28
53
Ethanol 85%
O. nerka age-1
1
1
7
7
7
93
93
Ethanol 85%
Larval fish
10
0
7
12
23/07/2006
Dip net
Formalin
Sculpin
1
1
1.48
Beach sceine
Formalin
Stickleback
28
28
0.71
Live
Stickleback
31
0
6
6
122
0
Formalin
Minnow trap(s)
RIC gill net
Swed gill net
Live
Sculpin
Stickleback
Formalin
Sculpin
3
3
Live
Sculpin
1
0
0.12
0.15
0.23
0.38
1
93
10
10
4
7.5
1
1.4
1.48
1.48
1
53
0.23
1.53
28
41
2.7
6
28
3.2
3.1
23
32
122
49
0.8
4.4
39
59
3
52
10.3
4.2
1
60
7.1
53
53
29
52
0
0.23
1.36
0.07
0.5
0.07
0.2
0.15
1.2
0.34
1.59
49
57
60
60
Live
Cutthroat trout
1
0
1
350
Live
Cutthroat trout
26
0
25
352
Ethanol 85%
O. nerka age-1
5
5
11.14
4.59
3.7
6.23
16.32
5
105
11.6
9.3
91
115
Ethanol 85%
O. nerka age-2+
2
2
57.62
3.37
0.37
57.35
57.88
2
173
31.8
3.5
170
175
Cutthroat trout
3
0
3
476
81.8
32.9
438
496
Live
17.3
42.1
350
350
190
410
Appendix 4. Summary of captured fish for each survey by capture gear, preservative, and taxa (Continued).
Catch
Lake/Date
Gear
Tankeeah (lower)
Trawl (2mx2m)
18/09/2006
Swed gill net
Tankeeah (upper)
19/09/2006
Trawl (2mx2m)
Fish State
n
n
Formalin
O. nerka age-0
10
10
2.35
0.63
0.89
1.41
4.32
Ethanol 85%
0.42
0.86
n
mean
95CI
SD
min
max
10
57
4.6
6.5
50
71
3.5
7.3
44
77
120
19
2.64
0.81
4.23
19
65
1
1
0.37
0.37
0.37
1
34
34
34
Ethanol 85%
Stickleback
1
1
0.2
0.2
0.2
1
29
29
29
Formalin
O. nerka age-0
1
1
6.34
6.34
6.34
1
80
80
80
Formalin
Stickleback
1
1
1.55
1.55
1.55
1
51
51
51
Formalin
Coho salmon
1
1
8.64
8.64
8.64
1
82
82
82
O. nerka age-0
4
4
1.94
0.52
0.32
1.54
2.33
4
60
4.5
2.8
56
62
Stickleback
7
7
1.62
0.23
0.25
1.2
1.88
7
55
1.6
1.7
52
57
O. nerka age-1
1
1
3.41
3.41
3.41
1
74
Dolly Varden
9
0
9
111
9.7
12.7
5.6
6.7
Ethanol 85%
Ethanol 85%
Live
sockeye = adult/jack sockeye
max
19
Trawl (2mx2m)
NPM = Northern pikeminnow
min
Stickleback
Minnow trap(s)
b
SD
O. nerka age-0
26/07/2006
a
95CI
Formalin
Whalen
Swed gill net
mean
Fork length (mm)
Taxa
Formalin
RIC gill net
Weight (gm)
O. nerka age-1
8
8
9.34
Live
Ethanol 85%
Coho salmon
1
1
42.11
Live
Dolly Varden
19
9
39.4
O. nerka age-1
1
1
13.25
Ethanol 85%
1.37
23.92
1.64
34.15
6.69
11.74
8
100
42.11
42.11
1
141
16.02
117.47
19
189
13.25
13.25
1
116
47.8
99.1
74
74
94
131
89
112
141
141
96
494
116
116
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008).
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Date
Fish Taxa
N
(#)
Alastair
14-Sep-09
O. nerka, age-0
2
41
0.85
25
Alastair
14-Sep-09
O. nerka, age-1
3
78
5.2
5
Alastair
14-Sep-09
Stickleback
50
48
1.27
23
Alastair
14-Sep-09
O. nerka, mix of age-0 & 1
22
69
3.47
2
Azuklotz
27-Aug-03
O. nerka, age-0
13
72
4.77
Bear
28-Aug-03
O. nerka, age-0
3
49
1.57
Water Type
Lake
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Diacyclops
Eubosmina
Insect
Diacyclops
Eubosmina
Insect
Diacyclops
Daphnia
Eubosmina
Insect
Diacyclops
Eubosmina
Insect
35.3
164.0
2.0
10.0
28.3
6.3
83.2
1.9
90.3
0.1
11.6
31.3
1.4
0.11199
0.17703
0.39655
0.02199
0.03079
1.25554
0.17584
0.01707
0.1053
0.01983
0.02208
0.03623
0.27937
17.6
81.5
1.0
22.4
63.4
14.2
47.4
1.1
51.4
0.1
26.2
70.6
3.2
16.3
25.8
57.8
1.7
2.4
96.0
55.3
5.4
33.1
6.2
6.5
10.7
82.7
86
Diacyclops
Daphnia
Bosmina
76.2
1840
11.5
0.13248
11.2207
0.057
4
95.5
0.6
1.2
98.3
0.5
63
Diacyclops
Daphnia
Bosmina
Heterocope
Insect
37
49
2
5.5
46
0.09836
0.57435
0.00818
0.51079
11.1118
25.2
33.3
1.4
3.7
31.3
0.8
4.6
0.1
4.1
89.4
Clear
121
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
Leptodora
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
7.5
0.12488
5.1
1
0.8
12.1
10.4
0.1
0.1
2.8
0.1
0.21576
2.92289
0.60495
0.00103
0.0129
0.67651
0.00167
6.2
93.8
77
0.7
0.7
20.7
0.7
6.9
93.1
46.6
0.1
1
52.2
0.1
26-Aug-03
Redside shiner
10
84
8.19
23
Bear
28-Aug-03
Pygmy whitefish
10
62
3.31
30
Elbow
20-Sep-07
O. nerka, age-0
10
78
5.03
58
Diacyclops
Daphnia
Eubosmina
Insect
2.3
1569.4
9.9
4.3
0.00517
14.0493
0.0347
0.25993
0.1
99.0
0.6
0.3
0.04
97.9
0.2
1.8
Fred Wright
10-Sep-09
O. nerka, age-0
2
65
3.51
90
Diacyclops
Daphnia
Holopedium
Insect
Polyphemus
30.8
1026.9
26.9
11.5
34.6
0.08564
8.65654
0.09655
2.28768
0.07607
2.7
90.8
2.4
1.0
3.1
0.8
77.3
0.9
20.4
0.7
Johanson
12-Sep-04
O. nerka, age-0
30
49
1.34
22
Alona
Bosmina
Diacyclops
1.4
144.1
21.3
0.00126
0.20089
0.03617
0.8
84.9
12.5
0.5
71.3
12.8
122
Bear
Chironomid
Insect
Chironomid
Daphnia
Heterocope
Insect
Leptodora
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
123
Holopedium
Insect
3
0.1
0.00977
0.03355
1.7
0.1
3.5
11.9
11
3.4
0.1
0.04397
0.00436
0.0315
75.8
23.4
0.9
55.1
5.5
39.5
22.0
1.8
165.8
3.3
0.06234
0.00264
0.6911
0.75892
11.4
0.9
86.0
1.7
4.1
0.2
45.6
50.1
Johnston
01-Sep-05
O. nerka, age-0
23
38
0.63
7
Cyclopod
Bosmina
Insect
Kimsquit
13-Sep-07
O. nerka, age-0
23
46
1.28
28
Diacyclops
Eubosmina
Holopedium
Insect
Kitlope
16-Sep-07
O. nerka, mix of age-0 & 1
20
55
2.04
25
Alona
Chaoborus larvae
Chironomid
Diacyclops
Daphnia
Eubosmina
Insect
0.1
0.1
0.2
1.0
1.9
58.7
5.8
0.00002
0.01294
0.07657
0.00303
0.01418
0.16213
1.33967
0.2
0.1
0.3
1.5
2.9
86.5
8.5
0.001
0.8
4.8
0.2
0.9
10.1
83.3
Kitwanga
01-Sep-03
O. nerka, age-0
10
49
1.54
54
Chaoborus
Diaphanosoma
Daphnia
14
7
97.5
1.90525
0.01468
1.20571
9.6
4.8
66.8
52
0.4
32.9
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
Leptodiaptomus
Leptodora
07-Sep-09
Redside shiner
10
78
7.62
0
none
Kwinageese
07-Sep-09
Lake chub
4
122
21.19
3
Diacyclops
Daphnia
Eubosmina
Holopedium
Insect
Lakelse
14-Jul-03
O. nerka, age-0
16
56
1.7
35
Lakelse
25-Sep-04
O. nerka, age-0
20
70
4.38
29
Lakelse
05-Sep-05
O. nerka, age-0
20
64
3.81
39
Ceratopognid
Daphnia
Epischura
Chironomid
Diacyclops
Diaphanosoma
Daphnia
Epischura
Insect
Diacyclops
Daphnia
Epischura
124
Kwinageese
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
25.5
2
0.50398
0.0333
17.5
1.4
13.8
0.9
0.0
0.0
1.0
2.3
32.3
3.3
2.0
0.00303
0.01099
0.10035
0.01165
0.39653
2.5
5.5
79.1
8.0
4.9
0.6
2.1
19.2
2.2
75.9
0.4
152.8
2.5
0.6
21.3
21.5
43.8
215.6
2.3
4.2
286.2
1
0.05026
1.3599
0.03471
0.34872
0.05234
0.08035
0.41243
2.26294
0.23685
0.01014
2.761285
0.01221
0.2
98.2
1.6
0.2
7
7
14.3
70.7
0.8
1.4
97.3
0.3
3.5
94.1
2.4
10.3
1.5
2.4
12.2
66.7
7
0.0
3.4
0.0
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
Bosmina
Neomysis
125
Lonesome
11-Sep-07
O. nerka, age-0
20
56
1.99
52
Diacyclops
Daphnia
Diaptomus
Eubosmina
McDonnel
13-Sep-02
O. nerka, age-0
10
50
1.35
42
Acanthocyclops
Daphnia
Bosmina
Leptodiaptomus
Meziadin
17-Sep-09
O. nerka, age-0
20
59
2.37
35
Meziadin
17-Sep-09
O. nerka, age-1
40
96
10.43
23
Diacyclops
Daphnia
Diaptomus
Eubosmina
Insect
Diacyclops
Daphnia
Diaptomus
Eubosmina
Insect
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
2
0.75
0.00925
0.653502
0.7
0.3
0.0
0.8
3.8
427.5
4.6
5.2
0.00911
5.2775
0.03065
0.02433
0.9
96.9
1.0
1.2
0.2
98.8
0.6
0.5
10.5
417
3
34.5
0.02011
2.63841
0.00528
0.51409
2.3
89.7
0.7
7.4
0.6
83
0.2
16.2
133.4
306.6
3.8
8.8
2.5
241.9
179.6
2.9
18.3
3.6
0.49944
1.8933
0.02055
0.01976
0.49566
0.89366
1.03636
0.01302
0.04224
0.7081
29.3
67.4
0.8
1.9
0.5
54.2
40.2
0.7
4.1
0.8
17.1
64.6
0.7
0.7
16.9
33.2
38.5
0.5
1.6
26.3
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Date
Fish Taxa
N
(#)
Meziadin
17-Sep-09
O. nerka, mix of age-0 & 1
20
61
2.77
30
Morice
15-Sep-02
O. nerka, age-0
10
57
2.13
44
Morice
(main lake)
16-Sep-02
O. nerka, age-0
3
45
0.83
42
Morice
(Atna Bay)
23-Sep-09
O. nerka, age-0
10
73
4.6
35
Morice
(Atna Bay)
23-Sep-09
O. nerka, mix of age-0 & 1
6
84
7.77
48
Water Type
Lake
126
(Atna Bay)
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Diacyclops
Daphnia
Diaptomus
Eubosmina
Insect
137.7
15.5
0.5
119.1
0.9
0.44217
0.10265
0.00282
0.25489
0.18024
50.3
5.6
0.2
43.5
0.3
45.0
10.4
0.3
25.9
18.3
Diacyclops
Daphnia
Bosmina
Holopedium
Insect
Diacyclops
Bosmina
Holopedium
Insect
Diacyclops
Daphnia
Eubosmina
Holopedium
Diacyclops
Daphnia
Eubosmina
Holopedium
27.3
2.1
55.7
64.3
7
3.7
3
26
0.3
343.3
3.3
113.3
30.0
408.3
18.8
168.8
29.2
0.06772
0.01073
0.28078
0.85606
1.68226
0.00962
0.01814
0.41933
0.08051
1.08819
0.03484
0.4243
0.10758
1.29416
0.19598
0.6594
0.02639
17.5
1.4
35.6
41.1
4.5
11.1
9.1
78.8
1
70.1
0.7
23.1
6.1
65.1
3.0
26.9
4.7
2.3
0.4
9.7
29.5
58.1
1.8
3.4
79.5
15.3
65.8
2.1
25.6
6.5
50.0
7.6
25.5
1.0
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
Insect
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
2.1
0.41304
0.3
16.0
127
Slamgeesh
07-Sep-01
O. nerka, age-0
20
66
3.95
82
Acanthocyclops
Daphnia
Bosmina
Insect
Leptodiaptomus
12.3
1023
14
4.7
301
0.01873
9.41261
0.04768
1.12728
6.16614
0.9
75.5
1
0.3
22.2
0.1
56.1
0.3
6.7
36.8
Stephens
10-Sep-02
O. nerka, age-0
10
57
2
46
Diacyclops
Daphnia
Bosmina
Heterocope
Insect
Leptodiaptomus
6
4.9
9.3
19.1
7.1
111.8
0.01759
0.02937
0.02976
1.46054
1.71303
0.39017
3.8
3.1
5.9
12.1
4.5
70.7
0.5
0.8
0.8
40.1
47.1
10.7
Sustut
10-Sep-04
O. nerka, age-0
30
50
1.45
9
Alona
Amphipod
Bosmina
Diacyclops
0.7
0.3
170.9
0.7
0.0186
0.40742
0.15454
0.0044
0.4
0.2
99.1
0.4
3.2
69.7
26.4
0.8
Swan
06-Sep-02
O. nerka, age-0
7
47
1.1
28
Diacyclops
Daphnia
Bosmina
Heterocope
18.3
39.4
4.6
6.3
0.0702
0.35538
0.02215
0.33812
21.6
46.6
5.4
7.4
8
40.4
2.5
38.4
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Swan
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Holopedium
Leptodiaptomus
Diacyclops
Daphnia
Bosmina
Heterocope
Leptodiaptomus
Leptodora
0.6
15.4
9.8
27.8
63
1.5
7.9
0.8
0.00593
0.08833
0.03298
0.20065
0.28093
0.19353
0.02871
0.01249
0.7
18.2
8.8
25.1
57
1.4
7.1
0.7
0.7
10
4.4
26.8
37.5
25.8
3.8
1.7
O. nerka, age-1
10
70
3.53
18
Stained
Banks East
18-Sep-04
O. nerka, age-0
12
65
3.3
50
Diacyclops
Diaptomous
Epischura
Bosmina
Holopedium
0.9
1.8
88.4
1075
3.1
0.00279
0.0059
0.87078
2.02099
0.03245
0.1
0.2
7.6
91.9
0.3
0.1
0.2
29.7
68.9
1.1
Banks East
18-Sep-04
Stickleback
10
71
3.77
6
Amphipod
Diacyclops
Daphnia
Diaptomous
Epischura
Bosmina
0.1
0.1
0.1
0.2
0.2
4.5
0.02739
0.00012
0.00044
0.00097
0.00244
0.00926
1.9
1.9
1.9
3.9
3.9
86.5
67.4
0.3
1.1
2.4
6
22.8
128
07-Sep-02
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Date
Fish Taxa
N
(#)
Banks West
17-Sep-04
O. nerka, age-0
20
65
3.27
48
Banks West
17-Sep-04
Stickleback
15
65
3.33
36
Ecstall
25-Aug-05
O. nerka, age-0
3
43
1.11
25
Ecstall
25-Aug-05
Stickleback
20
53
1.48
12
Water Type
Lake
Diet Items
129
Diacyclops
Daphnia
Diaptomous
Epischura
Bosmina
Holopedium
Polyphemus
Ceriodaphnia
Diacyclops
Daphnia
Diaptomous
Epischura
Bosmina
Holopedium
Polyphemus
Alona
Cyclopod
Bosmina
Insect
Alona
Chironomid
Cyclopod
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
1.3
43.8
7.5
28.8
1577.5
3.8
3.8
9.3
3.3
342.3
2.7
14.3
500
1.3
5.3
0.00391
0.43626
0.02673
0.29349
3.78786
0.03894
0.00515
0.03725
0.00684
3.34741
0.01297
0.12645
1.34174
0.01385
0.00806
0.1
2.6
0.5
1.7
94.7
0.2
0.2
1.1
0.4
39
0.3
1.6
56.9
0.2
0.6
0.1
9.5
0.6
6.4
82.5
0.9
0.1
0.8
0.1
68.4
0.3
2.6
27.4
0.3
0.2
0.3
4.3
1
1
0.1
3.1
0.1
0.00295
0.0212
0.00101
0.24154
0.00004
2.0165
0.00028
5
65
15
15
0.8
25.6
0.8
1.1
8
0.4
90.6
0
95.6
0
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
Diacyclops
Bosmina
Insect
04-Sep-01
O. nerka, age-0
10
43
1.04
55
Evelyn
04-Sep-01
O. nerka, age-1
10
78
6.53
45
Evelyn
04-Sep-01
Stickleback
8
97
11.59
4
130
Evelyn
Acanthocyclops
Bosmina
Chironomid
Daphnia
Holopedium
Insect
Leptodiaptomus
Schapholoberis
Acanthocyclops
Bosmina
Chironomid
Daphnia
Insect
Leptodiaptomus
Polyphemus
Schapholoberis
Acanthocyclops
Bosmina
Chaoborus
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
0.5
7.9
0.4
0.00134
0.00767
0.08455
3.8
66
2.9
0.1
0.4
4
0.6
10.2
1.2
132.6
0.6
0.6
19.8
10.2
5.6
13.1
11.3
453.8
3.8
35.6
9.4
11.3
0.8
3
0.8
0.00116
0.01829
0.87515
0.77914
0.00623
0.14494
0.13321
0.02063
0.01086
0.02277
1.71948
2.22477
0.90585
0.22405
0.02291
0.01564
0.00145
0.00497
0.11624
0.3
5.8
0.7
75.4
0.3
0.3
11.3
5.8
1
2.4
2.1
83.5
0.7
6.6
1.7
2.1
0.7
2.7
0.7
0.1
0.9
44.2
39.4
0.3
7.3
6.7
1
0.2
0.4
33.4
43.2
17.6
4.4
0.5
0.3
0.1
0.4
9.6
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
Chironomid
Daphnia
Holopedium
Leptodiaptomus
Polyphemus
Schapholoberis
131
Hartley Bay
(Lower)
30-Aug-05
Stickleback
17
56
2.03
15
Acari
Chaoborus
Chironomid
Diaptomous
Bosmina
Insect
Keecha
04-Sep-08
O. nerka, age-0
40
55
2
59
Keecha
04-Sep-08
Stickleback
28
65
2.57
31
Diacyclops
Daphnia
Diaptomus
Epischura
Eubosmina
Insect
Leptodora
Ceratopognid
Daphnia
Diaptomus
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
0.8
98.3
0.8
3
0.8
1.5
0.3624
0.69495
0.00779
0.01352
0.00221
0.00637
0.7
89.7
0.7
2.7
0.7
1.4
30
57.4
0.6
1.1
0.2
0.5
3.9
2.9
0.2
0.1
1.1
0.7
0.00799
0.45534
0.00471
0.00018
0.00155
0.101
45
32.9
2
0.7
12.1
7.4
1.4
79.8
0.8
0
0.3
17.7
0.3
0.7
46.4
18.0
164.8
4.0
4.7
0.04
0.1
19.9
0.00088
0.00822
0.31462
0.09944
0.18936
0.79655
0.05016
0.00708
0.00085
0.08796
0.1
0.3
19.4
7.6
69.0
1.7
2.0
0.1
0.2
41.0
0.1
0.6
21.6
6.8
13.0
54.6
3.4
0.9
0.1
11.3
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
04-Sep-08
O. nerka, mix of age-0 & 1
10
62
2.78
60
Kitkiata
27-Aug-05
O. nerka, age-0
20
43
1
8
Kitkiata
27-Aug-05
Stickleback
20
49
1.2
13
Koeye
12-Sep-06
O. nerka, age-0
20
56
1.56
50
132
Keecha
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Epischura
Eubosmina
Insect
Leptodora
worm
Diaptomus
Epischura
Eubosmina
Leptodora
3.9
21.0
3.1
0.5
0.04
33.6
10.9
210.9
11.8
0.02712
0.02874
0.61711
0.00516
0.00331
0.22833
0.06398
0.23187
0.12659
7.9
43.2
6.4
1.0
0.1
12.6
4.1
78.9
4.4
3.5
3.7
79.4
0.7
0.4
35.1
9.8
35.6
19.5
Chironomid
Diacyclops
Bosmina
Insect
Chironomid
Chydorus
Bosmina
Insect
0.1
0.3
20.9
1.4
0.1
0.1
6.3
4.1
0.00764
0.00076
0.01736
0.34758
0.02642
0.00007
0.00916
0.9904
0.2
1.1
92.3
6.4
0.5
0.5
60
39.1
2.1
0.2
4.7
93.1
2.6
0
0.9
96.5
83.7
2.5
0.6
32.5
576.5
0.20123
0.46558
0.08742
0.11724
3.31575
11.7
0.3
0.1
4.5
80.7
4.7
11.0
2.1
2.8
78.1
Bosmina
Chaoborus larvae
Chironomid
Diacyclops
Daphnia
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Diet Items
N
(#)
Weight
(mg)
1.9
15.6
1.7
Daphnia
Diaptomus
Epischura
Eubosmina
Insect
Diaptomus
Epischura
Eubosmina
Alona
Diaptomus
Eubosmina
Holopedium
Insect
Alona
Daphnia
Diaptomus
Eubosmina
Holopedium
Insect
Diaptomus
Polyphemus
Schapholoberis
02-Sep-08
O. nerka, age-0
37
59
2.27
49
Kooryet
02-Sep-08
Stickleback
20
75
3.8
25
Moore
08-Sep-08
O. nerka, age-0
40
63
2.7
48
Moore
08-Sep-08
Stickleback
33
48
1.31
30
133
Kooryet
N
(%)
Weight
(%)
0.01194
0.03716
0.01051
0.3
2.2
0.2
0.3
0.9
0.2
0.9
681.1
210.8
192.8
5.4
61.7
22.5
665.0
0.00646
3.34798
1.37864
0.30733
1.06896
0.29293
0.15516
1.34297
0.1
62.4
19.3
17.7
0.5
8.2
3.0
88.8
0.1
54.8
22.6
5.0
17.5
16.4
8.7
75.0
0.1
1.9
38.5
8.2
22.0
0.1
0.1
1.5
61.5
11.1
7.7
0.00005
0.01222
0.03903
0.02389
4.3491
0.00004
0.00129
0.0095
0.06092
0.03229
1.51514
0.1
2.6
54.5
11.6
31.1
0.1
0.1
1.8
75.1
13.5
9.4
0.001
0.3
0.9
0.5
98.3
0.002
0.1
0.6
3.8
2.0
93.6
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Date
Fish Taxa
N
(#)
Namu
15-Sep-06
O. nerka, age-0
20
55
2.2
44
Namu
15-Sep-06
Stickleback
6
76
4.45
10
Red Bluff
24-Jul-06
O. nerka, age-0
13
39
0.42
22
Water Type
Lake
Diet Items
134
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Bosmina
Chaoborus larvae
Chironomid
Diacyclops
Daphnia
Diaptomus
Holopedium
Polyphemus
Schapholoberis
Bosmina
Chaoborus larvae
Diacyclops
Diaphanosoma
Daphnia
Holopedium
26.7
0.4
0.4
32.0
33.8
5.0
1.1
1.8
0.5
75.5
1.5
1.0
3.5
67.0
7.0
0.04635
0.06207
0.05683
0.0669
0.33887
0.02239
0.00438
0.00156
0.00105
0.13852
0.31931
0.00315
0.0166
0.2851
0.01437
26.3
0.4
0.4
31.5
33.3
4.9
1.0
1.7
0.5
48.6
1.0
0.6
2.3
43.1
4.5
7.7
10.3
9.5
11.1
56.4
3.7
0.7
0.3
0.2
17.8
41.1
0.4
2.1
36.7
1.8
Acanthocyclops
Bosmina
Chironomid
Daphnia
Diaptomus
Holopedium
6.5
2.9
0.1
3.5
46.2
2.2
0.01564
0.01013
0.01166
0.02395
0.31417
0.00898
10.5
4.8
0.1
5.8
75.3
3.5
4.1
2.6
3.0
6.2
81.7
2.3
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Date
Fish Taxa
N
(#)
Red Bluff
24-Jul-06
O. nerka, age-1
3
56
2.6
37
Red Bluff
24-Jul-06
Stickleback
20
43
0.86
22
Water Type
Lake
135
Tankeeah
(lower)
18-Sep-06
O. nerka, age-0
20
62
2.75
39
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Acanthocyclops
Bosmina
Daphnia
Diaptomus
Holopedium
Polyphemus
Schapholoberis
Acanthocyclops
Alona
Bosmina
Chironomid
Chydorus
Ceratopognid
Diacyclops
Diaptomus
unidentified egg
Insect
Nauplii
worm
19.2
211.5
19.2
198.1
88.5
5.8
17.3
20.3
5.5
1.3
1.2
17.1
0.9
0.1
0.9
1.0
0.8
0.2
0.4
0.01862
0.64306
0.20771
1.62935
0.36878
0.01399
0.06888
0.04025
0.00227
0.00558
0.14005
0.01594
0.19045
0.00043
0.00308
0.6
21.8
7.0
55.2
12.5
0.5
2.3
5.9
0.3
0.8
20.5
2.3
27.8
0.1
0.5
0.16597
0.00007
0.12075
3.4
37.8
3.4
35.4
15.8
1.0
3.1
40.9
11.1
2.6
2.4
34.6
1.7
0.2
1.8
2.0
1.5
0.3
0.8
Acanthocyclops
Alona
Bosmina
4.3
0.3
232.0
0.00598
0.00054
0.32135
1.4
0.1
78.3
1.1
0.1
56.5
24.2
0.01
17.6
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Water Type
Lake
Date
Fish Taxa
N
(#)
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
136
Tankeeah
(upper)
19-Sep-06
O. nerka, age-0
3
59
1.92
50
Tankeeah
(upper)
19-Sep-06
Stickleback
6
55
1.58
15
Diet Items
N
(#)
Weight
(mg)
N
(%)
Weight
(%)
Chaoborus larvae
Diacyclops
Diaphanosoma
Daphnia
Diaptomus
Holopedium
0.8
0.8
5.3
0.3
7.5
45.3
0.12414
0.00183
0.0047
0.0025
0.03447
0.0735
0.3
0.3
1.8
0.1
2.5
15.3
21.8
0.3
0.8
0.4
6.1
12.9
Acanthocyclops
Bosmina
Diaphanosoma
Daphnia
Diaptomus
Holopedium
Polyphemus
Acanthocyclops
Bosmina
Chaoborus larvae
Chironomid
Diaptoms
Holopedium
35.0
377.5
10.0
2.5
287.5
17.5
2.5
1.8
4.7
0.2
0.2
3.7
0.2
0.05311
0.48273
0.00751
0.02504
1.8312
0.03024
0.00215
0.00265
0.00772
0.02759
0.02526
0.01546
0.00069
4.8
51.5
1.4
0.3
39.2
2.4
0.3
17.2
43.8
1.6
1.6
34.4
1.6
2.2
19.8
0.3
1.0
75.3
1.2
0.1
3.3
9.7
34.8
31.8
19.5
0.9
Appendix 5. Stomach contents of fish caught during surveys of the study lakes and from surveys in Hume and MacLellan (2008)
(Continued).
Fish
Mean
Mean
Length Weight
(mm)
(g)
Mean Diet Items per Fish
Mean
Fullness
(%)
Date
Fish Taxa
N
(#)
07-Sep-09
O. nerka, age-0
2
51
1.51
50
Bowser
07-Sep-09
O. nerka, mix of age-0 & 1
36
64
3.24
53
Kitsumkalum
05-Sep-05
O. nerka, age-0
6
63
2.33
Motase
30-Aug-03
O. nerka, age-0
5
44
Motase
30-Aug-03
O. nerka, age-1
5
70
Water Type
Lake
Glacially Turbid
Bowser
Diet Items
Weight
(mg)
N
(%)
Weight
(%)
Diacyclops
Insect
Diacyclops
Insect
2.5
32.0
217.9
14.5
0.00715
6.34442
0.84506
2.87606
7.2
92.8
93.8
6.2
0.1
99.9
22.7
77.3
22
Chaoborus
Cyclopod
Daphnia
Diaptomous
Insect
0.3
2.1
1.2
67.3
16.1
0.04613
0.00651
0.00959
0.33624
3.88199
0.3
2.4
1.4
77.4
18.5
1.1
0.2
0.2
7.9
90.7
1.1
10
4.38
37
Chironomid
Diacyclops
Insect
Diacyclops
Insect
0.4
16.4
5.6
0.2
31.6
0.02526
0.06323
1.03684
0.00122
7.63334
1.8
73.2
25
0.6
99.4
2.2
5.6
92.1
0
100
137
N
(#)
Appendix 6. Late summer zooplankton densities and biomass estimated from 160 um mesh, vertical haul, Wisconsin net samples.
Haul depth was 30 m, except where indicated.
Lake
stn
Date
(yymmdd)
Daphniidae
Bosminidae
Holopedium
Other
Cladocera
Cyclopoida
Calanoida
Macro
inverteb.
Nauplii
Other
Total
biomass (mg/m2)
138
Alastair
Batchellor
Bowser
Elbow
Fred Wrightc
Keechac
Kimsquit
Kitlope
Koeyec
Kooryet
Kwinageese
Lonesome
Meziadinb
Moore
Morice
Namuc
Red Bluff
Tankeeah lowerac
Tankeeah upperac
Whalenc
1
1
2
1
1
1
1
1
1
1
1
2
1
4
1
1
1
1
1
2009-09-15
2006-08-22
2009-09-04
2007-08-29
2009-09-10
2004-08-30
2007-08-27
2007-08-27
2006-09-01
2004-08-30
2009-09-08
2007-08-26
2009-09-17
2004-08-28
2009-09-21
2006-09-01
2006-08-22
2006-08-30
2006-08-30
2006-07-26
86
444
0.1
1,408
488
4
314
27
1,341
638
0.2
13
71
74
10
2
62
350
20
0.4
48
0.2
1
110
4
10
< 0.1
23
130
33
63
3
92
37
240
24
17
30
84
78
465
34
35
137
228
19
4
2
202
1
8
9
46
26
17
57
1
14
8
26
35
12
131
9
14
455
272
5
200
13
86
738
140
429
5
330
106
10
8
12
15
117
0.1
2
4
64
6
22
102
105
607
57
59
21
79
138
205
50
149
61
99
0.2
0.2
0.2
0.1
1
0.1
< 0.1
0.3
0.2
126
129
1
0.4
3
1
2
0.1
< 0.1
< 0.1
< 0.1
569
641
14
1,887
1,014
134
491
20
696
144
1,814
1,564
1,142
57
435
515
810
281
380
345
Appendix 6. Late summer zooplankton densities and biomass estimated from 160 um mesh, vertical haul, Wisconsin net samples.
Haul depth was 30 m, except where indicated (Continued).
Lake
stn
Date
(yymmdd)
Daphniidae
Bosminidae
Holopedium
Other
Cladocera
Cyclopoida
Calanoida
Macro
inverteb.
Nauplii
Other
Total
density (#/m2)
139
Alastair
Batchellor
Bowser
Elbow
Fred Wrightc
Keechac
Kimsquit
Kitlope
Koeyec
Kooryet
Kwinageese
Lonesome
Meziadinb
Moore
Morice
Namuc
Red Bluff
Tankeeah lowerac
Tankeeah upperac
Whalenc
a
c
1
1
2
1
1
1
1
1
1
1
1
2
1
4
1
1
1
1
1
2009-09-15
2006-08-22
2009-09-04
2007-08-29
2009-09-10
2004-08-30
2007-08-27
2007-08-27
2006-09-01
2004-08-30
2009-09-08
2007-08-26
2009-09-17
2004-08-28
2009-09-21
2006-09-01
2006-08-22
2006-08-30
2006-08-30
2006-07-26
20,744
60,094
11
181,117
56,422
333
64,988
3,086
115,091
83,463
285
2,513
18,624
14,007
7,433
751
15,614
322,110
6,626
11
9,007
40,041
31,851
37,567
867
62,366
29,045
60,399
7,643
8,983
37,424
19,010
70,170
214,547
28,054
32,949
83,538
180
2,343
22
872
8,561
2,022
398
49,234
6,899
4,415
92
20,752
1,614
512
5,109
12,214
17,290
16,193
20,422
285
16,182
4,178
29,339
44,649
14,987
b
haul depth = 20m
average of stations 1 & 2
Macro_Invertebtates are mostly Chaoborus, except in Fred Wright Lake, where they are Chironomids
106,256
4,591
5,544
362,997
110,417
5,101
95,056
9,897
63,746
305,501
79,211
125,035
4,189
137,920
72,603
5,786
6,145
8,794
10,860
31,921
22
7,524
640
18,759
101
111
40,980
28,312
139,351
11,704
8,585
8,367
177
34,950
53,999
14,251
40,316
6,755
163
1,547
404
1,177
228
2,760
514
11
1,023
703
548
291
36
1,568
15,428
4,357
5,536
635
321
171
211
449,311
113,972
5,587
554,668
218,609
57,397
181,857
11,325
246,341
57,962
529,090
214,672
226,066
52,868
159,955
219,367
320,481
107,588
149,689
152,848
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