in Southeast

in Southeast
Survey of Northern Abalone, Haliotis
kamtschatkana, Populations in Southeast
Barkley Sound, British Columbia, October 2002
t ••
J. Lessard, D. Brouwer, and J.P. Mortimor
Fisheries and Oceans Canada
Science Branch, Pacific Region
Pacific Biological Station
Nana.imo, British Columbia
V9T6N7
2004
.
<;.
Canadian Manuscript Report of
Fisheries and Aquatic Sciences 2685
1+1
Fisheries and Oceans
Canada
.
Peches et Oceans
Canada
Canada
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Canadian Manuscript Report of
Fisheries and Aquatic Sciences 2685
2004
SURVEY OF NORTHERN ABALONE, Haliotis kamtschatkana,
POPULATIONS IN SOUTHEAST BARKLEY SOUND,
BRITISH COLUMBIA, OCTOBER 2002
by
J. Lessard, D. Brouwer, and J.P. Mortimor l
Fisheries and Oceans Canada
Science Branch, Pacific Region
Pacific Biological Station
Nanaimo, British Columbia
V9T6N7
IBamfield Marine Sciences Centre
Barnfield, B.C. VOR IBO
ii
© Her Majesty the Queen in Right of Canada, 2004.
Cat. No. Fs 97-4 /2685E
ISSN 0706-6473
Correct citation for this publication:
Lessard, J., D. Brouwer, and J.P. Mortimor. 2004. Survey of northern abalone, Haliotis
kamtschatkana, populations in southeast Barkley Sound, British Columbia, October
2002. Can. Manuscr. Rep. Fish. Aquat. Sci. 2685: 11 p.
iii
ABSTRACT
Lessard, J., D. Brouwer, and J.P. Mortimor. 2004. Survey of northern abalone, Haliotis
kamtschatkana, populations in southeast Barkley Sound, British Columbia, October
2002. Can. Manuscr. Rep. Fish. Aquat. Sci. 2685: 11 p.
A survey was conducted to provide an estimate of the population size of emergent
northern abalone (Haliotis kamtschatkana) on the east side of Edward King Island, Deer Group,
Barkley Sound, British Columbia, during October 16-18, 2002. The estimated mean density for
emergent abalone of all sizes was 0.295/m2, while the estimated mean density for abalone 81-120
rom in shell length (SL) was 0.123/m2 . The estimated total population number (and lower 90%
confidence interval) of emergent abalone for all sizes was 21,075 individuals (15,744). The total
population number (and 90% confidence interval) of emergent abalone of the 81-120 rom SL
size range was estimated to be 8,791 individuals (6,220). This survey is compared to an earlier
one conducted in July 2000 at the same location.
Lessard, J., D. Brouwer, and J.P. Mortimor. 2004. Survey of northern abalone, Haliotis
kamtschatkana, populations in southeast Barkley Sound, British Columbia, October
2002. Can. Manuscr. Rep. Fish. Aquat. Sci. 2685: 11 p.
Un releve a ete effectue du 16 au 18 octobre 2002 pour estimer une population
d'ormeaux nordiques (Haliotis kamtschatkana) emergents dans Ie sud-est de la baie Barkley
(Colombie Britannique) ou leur presence est connue. La densite moyenne des ormeaux de toutes
tailles echantillonnes a ete estimee a 0,295/m2 , et celIe des ormeaux de longueur allant de 81 a
120 rom, a 0,123/m2 . La population total d'ormeaux emergents de toutes tailles a ete estime a 21
075 (limite inferieure de l'intervalle de confiance a 90%: 15744), et celIe des ormeaux de
longueur allant de 81 a 120 rom, a 8 791 (6 220). Les donnees recueillies lors d'un releve
precedent au meme endroit sont comparees.
INTRODUCTION
The northern, or pinto, abalone, Haliotis kamtschatkana, in British Columbia (BC) is
currently listed as a "threatened species" (i.e., "a species likely to become endangered if limiting
factors are not reversed") by the Committee on the Status of Endangered Wildlife in Canada
(COSEWIC). The northern abalone fishery was closed in 1990 to First Nations, recreational
divers and commercial fishers, due to conservation concerns (Campbell 1997). For these
reasons, all removals of northern abalone are considered a severe conservation risk.
As part of the strategy to rehabilitate northern abalone in BC, initial attempts have
included the development of aquaculture methodology for use in stock rebuilding initiatives
(Toole et al. 2002). This necessitates the removal of some mature abalone from the wild from a
number of areas to provide broodstock for seed production at aquaculture facilities in Be. To
estimate the abundance of abalone stocks in areas of interest, an independent assessment using
conventional survey methodology was required. Protocols to determine abalone abundance and
appropriate collection practices were developed in 1999 and used in the initial broodstock
collections for aquaculture (Lucas et al. 2002a,b,c,d,e). These protocols were reviewed and
modified based on the results of early broodstock surveys and collections (Lessard et al. 2002).
From this review a precautionary approach was recommended where the maximum number of
abalone that can be removed from any given site should be less than 1% of the lower 90%
confidence limit of the mature abalone population in the 81-120 mm shell length (SL) size range
estimated at that site. This recommendation differs from the early protocols where the size range
made available for collections was 91-110 mm SL.
The objectives of this study were to determine densities, size frequencies, and population
numbers of emergent northern abalone at east Edward King Island for future broodstock
collection(s) and compare these results to a previous broodstock survey completed in 2000
(Lucas et ai. 2002e).
MA TERIALS AND METHODS
FIELD :METHODS
This survey was conducted during daylight on October 16 - 18,2002, near Bamfield, BC
(Fig. 1). One location, east Edward King Island, was selected based on a previous survey (Lucas
et ai. 2002). The transect survey method (Lessard et ai. 2002) was used for this study. Transects
were randomly placed along the width of shoreline where the abalone population was to be
estimated. To avoid bias, these transect positions were determined before field work began. The
primary sampling unit was a transect, made up of a cluster of secondary units, or quadrats. Each
transect was 1 m wide and variable in length, depending on the slope of the seafloor. Prior to
entering the water, a lead line was laid perpendicular to shore from the boat from about 12 m to 0
m from chart datum. The secondary sampling unit consisted of aim x 1 m square quadrat that
was placed along the transect. Divers moved the quadrat parallel to the transect line, from deep
2
to shallow, and the number of "emergent" or "exposed" abalone, shell length (SL in mm) of each
abalone, depth, substrate type, and macroalgal cover were recorded every 2 m. Substrate was not
moved to search for cryptic abalone, since the majority of mature animals (i.e., ?70 mm SL) are
exposed (Sloan and Breen 1988; Cripps and Campbell 1998).
ANALYTICAL METHODS
All gauge depths were converted to depth (m) at chart datum. The survey results were
analyzed according to Fisheries and Oceans Canada methodology (Lessard et al. 2002). For
each site, the estimated mean density, ds (number/m2), of abalone was calculated as:
I
((cJ ql) * LI )
ds = --'I!.....---==--_ _
ILl
(1)
I
The standard error of the mean density, ses , was calculated as:
(2)
where:
n is the number of transects,
c/ is the number of abalone counted in transect t,
q/ is the number of quadrats sampled in transect t,
L, is the length of transect t,
"[ is the mean transect length,
T is the total possible number of transects that can be sampled in the surveyed area and is equal
to the site width, defined as the distance between the two furthest shoreline points used when
generating random transects.
The expression
~1-;
is nearly equal to one, because the sample size n is usually small
compared to T. This method accounts for the variable length of transects and for the variable
proportion of quadrats surveyed along each transect.
To estimate the mean density (Equation 1) and standard error (Equation 2) for a specific
size group (i) (i.e., 81-120 mm SL), the value c/ was substituted with Cli, the counts of size group
i in transect t.
At each site, the lower 90% confidence intervals of the mean density (L90Cl), for all
sizes or for a particular size group (81-120 mm SL) of abalone, were calculated using bootstrap
methods (Davidson and Hinkley 1997).
The estimated total number of abalone at each site (X), the population, was calculated as:
3
x =L90CI * A
(3)
where A is the estimated area (m2) of the surveyed site and was calculated as:
I*T
(4)
The population estimates were necessary to determine the number of abalone that could
be collected for broodstock. However, the population estimates in 2000 and 2002 were not
tested for differences as these values were derived from density and area estimates. The latter
are somewhat artificial values based on the mean transect length and site width. Mean SL were
compared between the 2000 and 2002 surveys by a two samples t-test. Density estimates were
not normally distributed and a Kolmogorov-Smirnov two-sample non-parametric test was used
to compare between the two surveys.
RESULTS
BROODSTOCK SURVEY OCTOBER 2002
Edward King Island is moderately exposed to winds and storms, with normal ground
swells. The substrate consisted of boulders and bedrock, with some cobble, gravel, sand and
shell (see Table 1 in Lucas et al. 2002e). The slope of the substrate ranged from 8 - 49% (Table
1). The macroalgal canopy consisted mostly of Nereocystis Iuetkeana along with some
Macrocystis integrifolia. The predominant macroalgal understory species were Laminaria spp.
followed by Pterygophora califomica, Phyllospadix scouleri, and Eisenia arborea. Articulated
coralline algae were the most common turf algae and encrusting coralline algae were abundant as
bottom cover.
The depths surveyed ranged from 0 to 13 m from datum (Table 1). One hundred eight
abalone were counted in 365 quadrats along the 15 transects surveyed. All transects surveyed
had emergent abalone. The densities of emergent abalone ranged from 0.094 to 0.684
abalone/m2 for all sizes and 0.000 to 0.400 abalone/m2 for the 81-120 rnm SL size range.
COMPARISON BETWEEN THE JULY 2000 AND OCTOBER 2002 SURVEYS
When looking at the 2000 survey data in Lucas et al. (2002e), errors were found and
corrected. The results used in the analyses and comparisons of this document are from the
corrected values.
At east Edward King Island, the shell lengths of abalone ranged from 38 to 114 rnm in
2000 and from 20 to 122 rnm in 2002 (Fig. 2). The mean size of emergent abalone in 2000 was
87 rnm SL which was significantly larger (P<O.OOI) than the mean SL of 74 rnm in 2002.
4
The estimated mean total density of emergent abalone of all sizes was 0.295± 0.051/m2 in
2002 and was not significantly different (P>0.5) from the density of 0.235± 0.049/m 2 that was
estimated in 2000 (Table 2). For the mature animals in the size range of 81-120 mm SL, the
mean density of 0.123±O.0271m2 in 2002 was not significantly different (P>0.1) from the 2000
estimate of 0.179±O.044/m2 • The mean population estimate of 21,075 emergent abalone in 2002
was almost identical to the population estimate in 2000 (21,161). In 2002, the mean estimate of
the number of emergent abalone in the 81-120 mm SL size range was 8,791 which was about
half of that estimated in 2000 (16,086). This difference was due to a shorter mean transect
length, used in estimating the surveyed area, and to a smaller density of abalone in the 81-120
mm SL size range (Table 2).
DISCUSSION
The mean SL in 2002 was significantly smaller than the mean in 2000. This was
probably due to an increase in the proportion of small animals in 2002 and a greater proportion
of large abalone in 2000 (Fig. 2). The proportion of the 81-120 mm SL abalone was 76% of the
total density in 2000 compared to 42% in 2002. As a result of this difference, as well as a
decrease in the mean transect length, the calculated number of abalone that could be collected for
broodstock was smaller in 2002, despite a small increase in total density. The decrease in the
proportion of abalone within the 81-120 mm SL size range could be a result of two previous
broodstock collections at this location. A total of 53 abalone were collected in the 90-110 mm
size range after the 2000 survey (Lessard et ai. 2002). Most likely other factors - such as sea
otters and sea star predation, survey season and poaching - also contributed to the decrease in the
proportion of larger abalone as the number of abalone removed was small. Although cryptic
abalone were not searched for in these surveys, the 2002 results showed some encouraging
recruitment (abalone <70 mm SL) (Fig. 2). The decrease in mean transect length is probably due
to transect placement as the depth range is similar between both surveys (Table 1 and -1 to 15 m
in 2000 (Lucas et ai. 2002». Using the mean transect length to estimate the surveyed area was
found to be more conservative (smaller area, therefore smaller population estimates) than other
methods (Lessard et ai. 2002).
A conservative estimate of the 81-120 mm SL population numbers of 6,220 emergent
abalone was provided by the lower 90% confidence interval (L90CI) for the mean. The resulting
potential number of abalone (i.e., <1 % of estimated L90CI (Lessard et ai. 2002» to be removed
for broodstock is 62 individuals.
The total emergent abalone density estimated from the 2002 survey was lower than the
estimate of 0.56/m2 in 1984 at the same location (Emmett and Jamieson 1988). The 2002 total
density estimate was also lower than the estimate of 0.37/m2 (day time) found at Eagle Bay, near
Barnfield (Mortimor et ai. 2003), but higher than densities found at other locations in the Deer
Group (0.04-0.22/m 2 , Watson 1993; 0.01-0.07/m2 , Lucas et ai. 2002). Since these low densities
are well below those recommended to ensure sustainable populations (Breen 1986; Campbell
1997), the removal of any abalone from these areas must be considered with caution.
5
ACKNOWLEDGMENTS
We thank B. Lucas for providing the first draft of this document; A. Corbett, M. DeRoos,
J. Pegg, M. Saunders, M. Stoeckle and D. Tzotzos for diving; and Chris Pearce as well as Jason
Dunham for reviewing the manuscript.
REFERENCES CITED
Breen, P.A. 1986. Management of the British Columbia fishery for northern abalone (Haliotis
kamtschatkana). Can. Spec. Publ. Fish. Aquat. Sci. 92: 300-312.
Campbell, A. 1997. Possible criteria for reopening the northern abalone (Haliotis
kamtschatkana) fishery in British Columbia. Can. Stock Assess. Sec. Res. Doc. 1997/64:
47 p.
Cripps, K. and A. Campbell. 1998. Survey of abalone populations at Dallain Point and Higgins
Pass, central coast of British Columbia, 1995-96. Can. Manuscr. Rep. Fish. Aquat. Sci.
2445: 31 p.
Davidson, A.C. and D.V. Hinkley. 1997. Bootstrap Methods and their Application. Cambridge
University Press, Cambridge. 578 p.
Emmett, B. and GS. Jamieson. 1988. An experimental transplant of northern abalone, Haliotis
kamtschatkana, in Barkley Sound, British Columbia. Fish. Bull. 77: 95-105.
Lessard, J., A. Campbell, and W. Rajas. 2002. Survey protocol for the removal of allowable
numbers of northern abalone, Haliotis kamtschatkana, for use as broodstock in
aquaculture in British Columbia. Can. Sci. Advisory Secret. Res. Doc. 2002/126. 41 p.
Lucas, B.G, D. Brouwer, and A. Campbell. 2002a. Survey of northern abalone, Haliotis
kamtschatkana, populations at Malcolm Island and Cormorant Island, British Columbia,
October 1999. [Revised]. Can. Manuscr. Rep. Fish. Aquat. Sci. 2620: 10 p.
Lucas, B.G, D. Brouwer, and A. Campbell. 2002b. Survey of northern abalone, Haliotis
kamtschatkana, populations near Kitkatla, British Columbia, March 2000. [Revised].
Can. Manuscr. Rep. Fish. Aquat. Sci. 2622: 11 p.
Lucas, B.G, A. Campbell, and D. Brouwer. 2002c. Survey of northern abalone, Haliotis
kamtschatkana, populations in Lotbiniere Bay, British Columbia, March 2000. [Revised].
Can. Manuscr. Rep. Fish. Aquat. Sci. 2621: 10 p.
Lucas, B.G, A. Campbell, and D. Brouwer. 2002d. Survey of northern abalone, Haliotis
kamtschatkana, populations at Chrome and southern Denman Island areas, May - June
2000 and May 2001. Can. Manuscr. Rep. Fish. Aquat. Sci. 2624: 13 p.
6
Lucas, RG, A. Campbell, D. Brouwer, S. Servant, and N. Webb. 2002e. Survey of northern
abalone, Haliotis kamtschatkana, populations in southeast Barkley Sound, British
Columbia, July 2000. [Revised]. Can. Manuscr. Rep. Fish. Aquat. Sci. 2623: 11 p.
Mortimor, J.P., c.R. Henderson, and GR.D. Elliott. 2003. Night and day surveys of a northern
abalone (Haliotis kamtschatkana) population in Eagle Bay, British Columbia. Can. Tech.
Rep. Fish. Aquat. Sci. 2482: 49-64.
Sloan, N.A. and P. A. Breen. 1988. Northern abalone, Haliotis kamtschatkana, in British
Columbia: fisheries and synopsis of life history information. Can. Spec. Pub!. Fish.
Aquat. Sci. 103: 46 p.
Toole, J., R Adkins, E. Bornhold, J. Boutillier, G Caine, A. Campbell, A. Castledine, L. Convey,
C. Cote, P. Coulson, T. Down, K. Francis, H. Gill, R. Harbo, H. Holmes, R Jubinville, D.
Lawseth, B. Lucas, A. Morgan, G Parker, and J. Rogers. 2002. National Recovery
Strategy for the Northern Abalone (Haliotis kamtschatkana) in British Columbia.
Fisheries and Oceans Canada. 22 p. (http://www-comm.pac.dfo­
mpo.gc.calpages/consultations/fisheriesmgmt/ abalone/AbaloneRecovStrategy e.htm)
Watson, J. 1993. The effects of sea otter (Enhydra [utris) foraging on shallow rocky communities
off northwestern Vancouver Island, British Columbia. Ph.D. Thesis, University of
California, Santa Cruz. 169 p.
Transect
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Date
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 16
Oct 17
Oct 17
Oct 18
Oct 18
Time
Bottom
Depth (m)
Start Finish Time (min) Min Max
09:11 10:12
61
0
9
09:42 10:41
2
13
59
10:35 10:55
20
1
8
11:21 12:07
46
4
8
11:05 11:34
29
0
9
12:06 12:50
44
0
6
12:42 13:26
44
1
9
13:02 14:00
58
0
8
14:13 14:39
26
3
9
14:30 14:55
10
25
0
7
15:00 15:36
36
0
09:46 11:05
79
2
10
12:27 13:25
1
58
8
09:44 10:42
58
0
8
11:35 12:20
45
2
6
12
49
24
16
24
9
30
10
29
27
11
10
16
15
8
(%)
Slope
#of
Transect
Quadrats Leng;th (m)
73
37
21
11
16
31
25
13
20
39
37
73
15
29
44
87
11
21
37
19
32
63
34
67
23
45
27
53
26
51
Total # of Abalone
all sizes 81·120 mm
4
4
6
1
1
8
5
1
2
8
7
3
6
6
2
5
2
5
5
13
0
3
15
6
11
8
2
3
9
2
Densitv (#/m2)
all sizes 81-120 mm
0.108
0.108
0.545
0.091
0.500
0.063
0.385
0.077
0.400
0.100
0.189
0.081
0.400
0.400
0.114
0.045
0.455
0.182
0.684
0.263
0.094
0.000
0.441
0.176
0.478
0.348
0.111
0.074
0.346
0.077
Table 1. Dive summary for abalone transects surveyed off east Edward King Island, Barkley Sound, October 16-18, 2002.
-....l
8
Table 2. Mean densities and population estimates of emergent abalone from east Edward
King Island, Barkley Sound, BC, in July 2000 and October 2002.
2002
2000
Number of Transects
Mean Transect Length
Shore Width
Surveyed Area (m2)
11
!?~!!sit~~!_~_l!!!J~~al()~~~IE:L___
Mean
SE
L90% CI
Density 81-120 mm (abalone/m2)
Mean
SE
L90% CI
.............
.
15
47.7
1,500
71,500
59.9
1,500
89,864
,., .. _" .. ,,~,,-,',~'-'~'~"-
'~'''~~,-,'-'-~'--~~--
0.235
0.049
0.161
0.295
0.051
0.220
0.179
0.044
0.114
0.123
0.027
0.087
................ .......
.
J'0I''!!'!IionaJ!s~_
~-- -T~~-------Mean
21,161 I-----------~
21,075
L90% CI
:J:»~Pllllltion 81-120 mm SL
Mean
L90% CI
Allowable for collection (1 %)
14,423
...
15,744
. ................
16,086
10,209
102
8,791
6,220
62
9
.'a...
'w
00
~-I.----r----r------,~-""~
..,. 125°14'
125°13'
125°12'
Figure 1. Abalone survey area (dashed line), Edward King Island, Barkley Sound, Be.
10
This page purposely left blank
11
2000
8-,------------------------------,
7
N=79
MeanSL= 87 mm
6
11
21
31
41
51
61
71
81
91
101
111
121
Shell length (mm)
2002
8,-------------------------------,
7
N=108
Mean SL = 74 mm
6
3
11
21
31
41
51
61
71
81
91
101
111
121
Shell length (mm)
Figure 2. Size frequencies of emergent abalone found in quadrats during dive surveys off
east Edward King Island, Barkley Sound, Be, are shown for July 2000 and October 2002.
Number of abalone (N) and mean shell length (SL) in mrn are shown.
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