Survey of Northern Abalone, Vancouver Island, British Columbia, May 2003 Haliotis kamtschatkana,

Survey of Northern Abalone, Vancouver Island, British Columbia, May 2003 Haliotis kamtschatkana,
Survey of Northern Abalone, Haliotis
kamtschatkana, Populations Along North-West
Vancouver Island, British Columbia, May 2003
M. Atkins and J. Lessard
Fisheries and Oceans Canada
Science Branch, Pacific Region
Pacific Biological Station
Nanaimo, British Columbia
V9T6N7
2004
Canadian Manuscript Report of
Fisheries and Aquatic Sciences 2690
1+1
Fisheries and Oceans
Canada
PEiches at Oceans
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Canadian Manuscript Report of
Fisheries and Aquatic Sciences 2690
2004
SURVEY OF NORTHERN ABALONE, Haliotis kamtschatkana, POPULATIONS
ALONG NORTH-WEST VANCOUVER ISLAND, BRITISH COLUMBIA, MAY 2003
by
M. Atkins and J. Lessard
Fisheries and Oceans Canada
Science Branch, Pacific Region
Pacific Biological Station
Nanaimo, British Columbia
V9T6N7
ii
© Her Majesty the Queen in Right of Canada, 2004.
Cat. No. Fs 97-4 12690E
ISSN 0706-6473
Correct citation for this publication:
Atkins, M. and Lessard, J. 2004. Survey of northern abalone, Haliotis kamtschatkana,
populations along north-west Vancouver Island, British Columbia, May 2003.
Can. Manuscr. Rep. Fish. Aquat. Sci. 2690: 12 p.
111
ABSTRACT
Atkins, M. and Lessard, J. 2004. Survey of northern abalone, Haliotis kamtschatkana,
populations along north-west Vancouver Island, British Columbia, May 2003.
Can. Manuscr. Rep. Fish. Aquat. Sci. 2690: 12 p.
Northern, or Pinto, abalone, Haliotis kamtschatkana, have been protected by
harvest closures since 1990 due to low population levels. Index site surveys have been
preformed by Fisheries & Oceans Canada since 1978 to monitor the recovery of the
abalone populations in British Columbia. This survey was the first on the north-west
coast of Vancouver Island, and will be used as reference for future surveys in this area.
Northern abalone were found at eight (25%) of the 32 sites surveyed. The density in
Quatsino Sound was 0.21 ± 0.04 abalone I m2 , which is close to the densities surveyed
in 2002 in the Queen Charlotte Islands (0.34 ± 0.06 abalone/m 2), and in 2001 on the
central coast (0.27 ± 0.04 abalone/m 2). In total, nearly 60% of the individuals sampled
were immature «70 mm shell length); the large proportion of immature individuals
shows a potential for a future recruitment pulse, however, population increases will be
small until such time.
RESUME
Atkins, M. and Lessard, J. 2004. Survey of northern abalone, Haliotis kamtschatkana,
populations along north-west Vancouver Island, British Columbia, May 2003.
Can. Manuscr. Rep. Fish. Aquat. Sci. 2690: 12 p.
La peche de I'ormeaux nordique, Haliotis kamtschatkana, de la Colombie­
Britannique est comph3tement fermee depuis 1990 afin d'assurer la conservation de
I'espece. Des releves a des sites indicateurs ont ete effectues par Peches et Oceans
Canada depuis 1978 pour surveiller Ie retablissement des populations d'ormeaux. Le
releve decrit ici est Ie premier effectue sur la partie nord-ouest de la cote de I'ile de
Vancouver et sera utilise comme reference pour de futurs releves a cet endroit. Des
ormeaux etaient presents a 8 (25%) des 32 sites echantillonnes. La densite dans Ie
detroit de Quatsino etait de 0.21 ± 0.04 ormeau/m 2 • Cet estime est similaire aux
resultats des releves dans les iles de la Reine Charlotte en 2002 (0.34 ± 0.06
ormeau/m2 ) et de la cote centrale de la C.-B. en 2001 (0.27 ± 0.04 ormeau/m 2 ). En
incluant tous les resultats de ce releve, presque 60% des individus etaient immatures
«70 mm de longueur); la grande proportion de ces animaux demontrent un potentiel
pour un taux eleve de recrutement dans Ie futuro Cependant, la croissance de
population sera faible d'ici-Ia.
INTRODUCTION
The northern, or pinto, abalone, Haliotis kamtschatkana, generally occurs in
patchy distributions along exposed or semi-exposed coastlines from Yakutat, Alaska to
Baja California (Sloan and Breen 1988; O'Clair and O'Clair 1998). In British Columbia
(BC), abalone were a traditional food source for First Nations, and were harvested by
recreational and commercial divers until 1990. Due to low stock numbers the
Department of Fisheries & Oceans Canada placed a complete ban on abalone
harvesting in December, 1990. Surveys of index sites along the central coast of BC and
the Queen Charlottes showed evidence of a 75-80% decline in abalone abundance in
the period of 1978-1990 (Thomas et al. 1990; Farlinger et al. 1991; Campbell 2000).
Despite harvest closures, their numbers remain low and in 1999 northern abalone was
listed as 'threatened' by the Committee on the Status of Endangered Wildlife in Canada
(Campbell 2000; Jamieson 2001).
The objective of this survey was to determine the population density and size
frequency of abalone populations on the north-west coast of Vancouver Island. To date
no systematic surveys to determine abalone abundance have been completed on the
north-west coast of Vancouver Island, primarily due to low historic fishery catches (9 t
between 1977 and 1990) (Harbo 1997). Past surveys focused on the central coast and
the Queen Charlotte Islands because oftheir higher reported fisheries catches; 497 t
and 752 t respectively between 1977 and 1990. The results of this survey may be used
in conjunction with other index site survey results in BC to establish baseline abalone
abundance data and evaluate the effectiveness of conservation efforts along the coast.
METHODS
The Canadian Coast Guard research vessel'CCGS Vector' acted as the Iive­
aboard platform from which daily operations commenced. Two smaller support vessels
transported two dive teams to and from the sites for four days in May, 2003. Both boats
were equipped with GPS to find the precise location of each pre-determined site.
A total of 50 sites were randomly chosen from Pacific Fishery Management
Areas 27 and 127 (Fig. 1); of these, 18 sites were removed due to unfavourable
abalone habitat conditions such as heavy wave exposure, or sand/gravel substrate.
The remaining 32 sites were sampled using the 'Breen' survey method (Breen and
Adkins 1979).
Once each site was located, divers placed a 1 m2 quadrat at the top of the abalone
habitat zone and then sampled 16 quadrats within a 7 m by 16 m area (4 rows of 4
quadrats). Vegetation was cleared from the substrate and all visible "exposed" abalone
were counted and measured. Divers also recorded the dominant algal species, substrate
type, depth and urchin counts. During past surveys divers turned boulders and rocks in
search of hidden or cryptic abalone, but during this survey, in an effort to conserve time
and increase sample size, only exposed abalone were recorded. Sampling only
2
exposed abalone is an efficient sampling strategy, since the majority of mature abalone
(i.e., ~70 mm shell length (SL)) are exposed (Campbell 1996; Cripps and Campbell
1998). If no abalone were seen by the eighth quadrat, the dive was aborted and the site
count was scored as zero. Each site was considered to be a single sample for the
density estimates, with the 16 quadrats per site as secondary sampling units.
All recorded depths were corrected for tide heights post survey. Abalone
densities were estimated as the number/m2 for total (all sizes), as well as for several
size categories: immature «70 mm); mature (~70 mm); pre-recruit (92-99 mm); new
recruit (100-106 mm) and legal (~1 00 mm SL). The smallest size at which 100% of
abalone are mature was found to be approximately 70 mm SL (Campbell et al. 1992).
Growth curves provided by Quayle (1971) and Breen (1986) were used to estimate pre­
recruit and recruit sizes for northern abalone. Densities of immature abalone should be
treated with caution due to the increased difficulty of detecting smaller individuals.
Tissue samples were taken from abalone collected at a single site (site 46) for
future DNA analysis. From each abalone, a small clip of epipodial tissue was taken and
preserved with 70%, or higher, ethanol. The results of the DNA analysis will be
presented elsewhere. The size frequency results are presented here, but are not
included in the density estimates as no area measurement, i.e. quadrat, was used while
collecting these animals.
RESULTS
A total of 32 sites were sampled along the north-west coast of Vancouver Island
in May of 2003. An average of 20 minutes (range 9-44 min) was spent sampling each
site (Table 1). The survey results were separated into 3 areas of similar habitat:
Quatsino Sound (n=13), Brooks Bay (n=5), and all other 'exposed' areas (n=14).
Exposed areas were characterized by bedrock substrate and heavy wave exposure.
Brooks Bay sites were slightly more protected, characterized by bedrock substrate, with
boulders and cobble substrate also present (Table 2). Sites surveyed in Quatsino
Sound were more sheltered, had more algae cover, and boulder was the dominant
substrate. Abalone were found in eight (25%) sites; seven of which were located in
Quatsino Sound, and one in Brooks Bay. Abalone were only observed in sites
containing bedrock with crevices, and/or boulders, which, in either case, could provide
refuge from predators (Table 2). Sea urchins were also found at all sites with abalone
(Table 1).
The total number of abalone sampled was 47; of these 28 (59.6%) were
immature (Table 3). The mean shell length was 59.1 mm; the smallest abalone
measured was 17 mm and the largest was 101 mm (Fig. 2). Only two (4.3%) were
above the historic legal harvest size of 100 mm SL.
The majority of abalone sampled were found in four meters or less of water (at
chart datum) (Fig. 3). The total mean density of abalone in the area surveyed was
3
0.0921m 2 ; Quatsino Sound had a density of 0.2121m 2 , and Brooks Bay a density of
0.038/m 2 • No abalone were found along the outermost exposed coastline. Urchins
were also counted. All species of urchin were grouped, but counts generally reflected
red sea urchin (Strongylocentrotus franciscanus) abundance as other species
(5. droebachiensis and S. purpuratus) were rare. The overall urchin density was
0.795/m 2 , with 0.4621m 2 in Quatsino Sound and 1.375/m2 in Brooks Bay.
A single site was chosen from which 84 additional abalone were collected and
sampled for DNA analysis. A size frequency graph was constructed (Fig. 4); the mean
shell length was 67.2 mm (SE=1.4 mm) with a minimum shell length of 35 mm and a
maximum of 100 mm. The size frequency may be biased due to divers preferentially
selecting larger individuals.
DISCUSSION
This was the first abalone survey on the northern region of Vancouver Island.
The overall observed population density (0.09 ± 0.04 abalone/m 2) in 2003 was relatively
low. The majority of sites where abalone were present were located in Quatsino Sound,
where the density estimate (0.21 ± 0.08 abalone/m 2) indicates similar population
densities to those observed in the 2002 Queen Charlotte Island (0.34 ± 0.06
abalone/m 2) (unpUblished) and 2001 Central Coast (0.27 ± 0.04 abalone/m 2)
(unpublished) index site surveys.
Approximately 60% of abalone surveyed were immature (Table 3) suggesting a
slow population increase until such time that the immature individuals reach sexual
maturity, at which time a recruitment pulse would be expected. Although larger
individuals were targeted for the DNA sample, all but one animal were smaller than 100
mm SL (Fig. 4). The small sizes could indicate stunted growth due to high exposure to
wave action and/or currents and low food supply (Sloan and Breen 1988). Population
structure may also be dictated by the presence of sea otters in the area. Larger
abalone tend to be less cryptic (Campbell 1996) and sea otters may be removing these
larger, more exposed abalone from the area.
Sea otters were first observed in 1989 in Quatsino Sound and in 1991 in the area
of Brooks Bay (Watson et al. 1997). The population is now well established in Brooks
Bay and during the last sea otter survey in 2003, rafts were observed around Drake
Island, well within Quatsino Sound (Linda Nichol, Pacific Biological Station, Nanaimo,
BC, V9T 6N7; pers. comm.).
Watson (1993, 2000) has studied the effect of sea otters (Enhydra lutris) on
nearshore ecosystems continuously between 1987 and 1998. Abalone densities
ranged from 0.2 ± 0.2 to 19.4 ± 5.0 abalone/20m 2 (0.01 to 0.97 abalone/m 2) in areas
with no otters or prior to their arrival, to densities <1 abalone/20m 2 where otters were
present. Abalone found in areas occupied by sea otters were restricted to crevices
inaccessible to foraging otters (Watson 1993). Even surveying only exposed abalone,
in 2003 abalone were present in areas where otters are established at higher abalone
4
densities than that estimated by Watson (1993) in areas with sea otters. This may be
the result of the relatively low densities which make abalone a scarce food resource for
sea otters and are therefore not selected as sea otters often exploit seasonally
abundant food resources (Watson et al. 1997). Since abalone densities prior to the
presence of sea otters within this area are unknown, the effect of sea otters on the
abalone population is only speculative.
At all the 2003 survey sites where abalone were present, urchins, mainly red sea
urchins, were found as well. This was expected as red sea urchin and abalone share
similar habitat characteristics (Tomascik and Holmes 2003). Urchin density from all
sites surveyed in 2003 (0.417/m 2) was low compared to urchin stock assessment
densities throughout the coast (densities ranged from 0.1 to 12.6 urchins/m2 ; Table 4 in
Campbell et al. 2000). The low urchin density observed in this study may be the result
of sea otter predation. The arrival of sea otters at 3 out of 4 permanently marked sites
in the 1993 study by Watson described above was followed by a decline in sea urchins
and an increase in algae. At the 4th site, Kyuquot Bay (PFMA 26, south of Brooks
Peninsula), sporadic foraging resulted in a patchy mosaic of urchins and algae.
This study suggests that abalone populations are small or non-existent on the
north-west coast of Vancouver Island, with the exception of Quatsino Sound and Brooks
Bay. Much of the coastline here is completely exposed to the open Pacific, and the
shallow subtidal may be too inhospitable for the abalone to survive outside of these
protected areas. For future surveys, we recommend that sites be selected within
Quatsino Sound and Brooks Bay areas alone. We suggest that all sites within these 2
areas be re-surveyed (with the exception of site 34, which was too protected and too
steep with the surrounding areas made up of gravel beach), with additional sites
surveyed in Brooks Bay.
ACKNOWLEDGEMENTS
Thanks to Doug Brouwer and Alan Campbell for survey design and logistics
support. Thanks also to Dimitri Tzotzos, Pauline Ridings, and James Paterson for
diving; the crew of the Vector for field assistance; and Linda Nichol and Leslie Barton for
reviewing the manuscript.
REFERENCES
Breen, P. A. 1986. Management of the British Columbia fishery for northern abalone
(Haliotis kamtschatkana). Can. Spec. Publ. Fish. Aquat. Sci. 92: 300-312.
Breen, P. A. and Adkins, B. E. 1979. A survey of abalone populations on the east
coast of the Queen Charlotte Islands, August 1978. Fish. Mar. Servo Manuscr.
Rep. 1490: 125 p.
5
Campbell, A 1996. An evaluation of abalone surveys off southeast Queen Charlotte
Island. Can. Tech. Rep. Fish. Aquat. Sci. 2089: 111-131 p.
Campbell, A 2000. Review of northern abalone, Haliotis kamtschatkana, stock status
in British Columbia. Can. Spec. Public. Fish. Aquat. Sci. 130: 41-50 p.
Campbell, A, Bureau, D., and Brouwer, D. 2000. Quota estimates for the 1998 red sea
urchin fishery in British Columbia. Can. Manuscr Rep. Fish. Aquat. Sci. 2516:
31 p.
Campbell, A, Manley, I., and Carolsfeld, W. 1992. Size at maturity and fecundity of the
abalone, Haliotis kamtschatkana, in northern British Columbia. Can. Manuscr.
Rep. Fish. Aquat. Sci. 2169: 47-65.
Cripps, K. and Campbell, A 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.
Farlinger, S.,.Thomas, G. A, Winther, I., and Carolsfeld, W. 1991. Abalone resurvey in
the Estevan Group and Aristazaballsland, June 1989. Can. Manuscr. Rep. Fish.
Aquat. Sci. 2104: 39 p.
Harbo, R. 1997. Abalone Dive Fishery (closed). Can. Manuscr. Rep. Fish. Aquat. Sci.
2369: 86-92
Jamieson, G. S. 2001. Review of status of northern abalone, Haliotis kamstchatkana,
in Canada. Canadian Field-Naturalist 115: 555-563
O'Clair, R. M. and O'Clair, C. E. 1998. Southeast Alaska's Rocky Shores - Animals.
Plant Press, Auke Bay, Alaska. 561 p.
Quayle, D. B. 1971. Growth, morphometry and breeding in the British Columbia
abalone (Haliotis kamtschatkana Jonas). Fish. Res. Bd Can. Tech. Rep. Ser.
279: 84 p.
Sloan, N. A. and Breen, P. A 1988. Northern abalone, Haliotis kamchatkana in British
Columbia: fisheries and synopsis of life history information. Can. Spec. Public.
Fish. Aquat. Sci. 103: 46 p.
Thomas, G., Farlinger, S., and Carolsfeld, W. 1990. Abalone resurvey in the southeast
Queen Charlotte Islands in 1990. Can. Manuscr. Rep. Fish. Aquat. Sci. 2099:
66-82.
6
Tomascik, T. and Holmes, H. 2003. Distribution and abundance of Haliotis
kamtschatkana in relation to habitat, competitors and predators in the Broken
Group Islands, Pacific Rim National Park Reserve of Canada. J. Shellfish Res.
22: 831-838.
Watson, J. C. 2000. The effects of sea otters (Enhydra lutris) on abalone (Haliotis
spp.) populations. In Workshop on Rebuilding Abalone Stocks in British
Columbia. Edited by A. Campbell. Can. Spec. Publ. Fish. Aquat. Sci. 130. pp.
123-132.
Watson, J. C. 1993. The effects of sea otter (Enhydra lutris) foraging on shallow rocky
communities off northwestern Vancouver Island, British Columbia. Dissertation,
University of California, Santa Cruz, Cal. 169 p.
Watson, J. C., Ellis, G. M., Smith, T. G., and Ford, J. K. B. 1997. Updated status of the
sea otter, Enhydra lutris, in Canada. Canadian Field-Naturalist 111: 277-286.
7
Table 1. Dive survey summary for abalone transects surveyed on the north-west coast
of Vancouver Island, May 2003.
Time
Start
Finish
Bottom
Time
13:58
10:31
13:33
14:02
11:11
9:43
12:49
14:50
13:23
15:45
14:12
12:57
14:43
14:34
10:59
13:47
14:26
11:33
10:11
13:12
15:07
13:33
16:13
14:21
13:41
15:07
36
28
14
24
22
28
23
17
10
28
9
44
24
0
1
1
0
1
0
1
0
0
0
1
0
3
Brooks Bay
11
May-09
15
May-09
19
May-09
26
May-09
50
May-09
Total (n=5)
12:26
11:23
11:43
10:49
11:47
12:37
11:33
11:53
11:19
12:04
11
10
10
30
17
Exposed Sites
2
May-06
6
May-07
May-06
7
8
May-07
14
May-07
17
May-07
28
May-06
31
May-06
33
May-07
36
May-07
38
May-07
43
May-07
45
May-06
48
May-07
Total (n=14)
12:11
8:30
11:54
14:33
8:54
15:04
11:23
11:24
15:44
12:15
11:16
9:42
14:04
9:17
12:37
8:40
12:18
14:50
9:03
15:20
11:39
11:38
15:57
12:40
11:38
10:05
14:28
9:35
26
10
24
17
9
16
16
14
13
25
22
23
24
18
Site Date
Quatsino Sound
May-07
1
4
May-08
5
May-07
9
May-08
May-08
10
12
May-08
13
May-08
20
May-08
24
May-08
25
May-07
34
May-08
46
May-08
47
May-07
Total (n=13)
AU Sites
Total (n=32)
Depth (m)
Min Max
#of
Quadrats
#of
Abalone
Density
#of
Urchins
Density
(#/m2 )
3
6
2
4
4
3
4
2
3
3
7
7
6
16
16
8
8
16
16
16
8
8
8
8
16
16
8
2
0
0
5
3
3
0
0
0
0
17
6
44
0.500
0.125
0.000
0.000
0.313
0.188
0.188
0.000
0.000
0.000
0.000
1.063
0.375
0.212
15
23
1
0
10
3
22
0
0
0
0
19
2
9S
0.938
1.438
0.125
0.000
0.625
0.188
1.375
0.000
0.000
0.000
0.000
1.188
0.125
0.462
-1
-1
2
0
0
3
1
5
6
2
8
8
8
16
8
0
0
0
3
0
3
0.000
0.000
0.000
0.188
0.000
0.038
0
0
0
1
1
2
0.000
0.000
0.000
0.063
0.125
0.038
3
1
3
1
2
-1
3
2
0
2
0
2
0
1
4
2
5
3
3
0
4
6
1
4
2
3
2
3
8
8
8
8
8
8
8
8
8
8
8
8
8
8
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0
0
73
0
0
0
81
0
0
0
0
0
0
0
154
0.000
0.000
9.125
0.000
0.000
0.000
10.125
0.000
0.000
0.000
0.000
0.000
0.000
0.000
1.375
47
0.092
251
0.795
(#/m2)
8
Table 2. Site descriptions of all 32 sites sampled on the north-west coast of Vancouver
Island, May 2003. The most common substrates are listed (1 =first, 2 =second, 3 =
third) where substrate code 1 =smooth bedrock, 2 = bedrock with crevices, 3 =
boulders, 4 =cobble, 5 =gravel, 6 = pea gravel, 7 =sand, 8 =shell. The algae are listed
by growth characteristics for the most common (Sp 1) and second most common (Sp 2)
with percentage cover (%) for each, where AG =Agarum sp, AC = articulated corallines,
CO = Costaria costata, DE = Desmarestia sp, IR = Iridaea sp (Maziella sp), LA =
Laminaria sp., LT = Laminaria setchellii, MA = Macrocystis integrifolia, NT = Nereocystis
luetkeana, PH = Phyllospadix sp, PT = Pterygophora califomica, RS = red branched, RF
=red foliose, RH = red filamentous.
Substrate
Site 1 2 3
Quatsino Sound
1
2 3
4
3 4
5
3 4 7
9
4 5 7
3 4 7
10
3 2
12
3 4 7
13
20
4 5 7
24
3 4
25
2
34
2 3 7
46
1 3 4
47
3 4 8
Brooks Bay
11
2 8
15
2
19
3 7
26
2 7
50
2
Exposed Sites
2
2 3
6
2 5
7
2 3 7
8
4 3 57
14
2
17
1 7
28
2 3 8
31
2 3
1 3 4
33
1 4
36
1 5
38
43
2 5
45
3 4
48
2
Slope
%
Spl
19
PT
MA
MA
MA
15
42
MA
MA
19
30
34
30
76
42
19
MA
46
27
27
36
23
MA
19
NT
MA
MA
PT
MA
PT
MA
MA
11
34
27
15
15
15
57
4
27
27
19
14
27
NT
MA
PT
PT
PT
Canopy
%
Sp2
%
Spl
50
0
10
0
50 PT 30
30
0
10
0
30
0
10
0
100
0
40
0
100
0
5
0
0
0
50 MA 10
LT
PT
AG
PT
PT
AG
AG
PT
DE
AG
PT
5
0
0
50
60
0
0
0
0
0
AG
PH
PH
MA
70
0
10
70
0
0
25
1
0
0
0
0
0
90
0
0
0
0
0
0
25
0
0
0
0
0
0
0
LT
LT
DE
LA
PT
LT
LA
PH
LA
PH
LA
LA
PH
LT
Understory
%
Sp2
10
40
0
90
20
70
90
100
40
5
50
50
80
100
100
50
10
LT
DE
DE
PH
100
10
DE
10
RB
0
20
0
25 CO
1
10
30 PT
30 PT
100
50 LT
10
PL
Turf
Sp2
Encrusting
%
Spl
%
%
%
0
0
0
0
0
70
0
0
0
0
0
0
DE
DE
10
0
0
0
0
10
80
0
0
10
70
80
70
10
80
60
70
10
60
60
70
90
90
DE
AC
AC
AC
PH
5
0
0
10
DE
80
10
10
10
10
0
0
20
0
100
100
0
10
AC
AC
AC
AC
AC
10
80
80
30
50
0
0
0
0
0
0
25
0
0
30
30
0
20
20
AC
PH
AC
30
50
RF
30
60
0
10
80
80
10
50
75
50
30
IR
AC
AC
RH
PH
AC
PH
RH
AC
DE
AC
DE
AC
AC
10
0
0
RB
AC
10
AC
LT
AC
RF
AC
0
0
0
0
0
20
5
60
80
80
0
50
0
30
20
0
0
0
80
0
0
75
0
40
90
60
90
20
70
0
100
100
90
80
80
75
0
60
9
Table 3. Mean shell lengths (mm SL) of exposed abalone of different size groups for all
transect surveys on the north-west coast of Vancouver Island, May 2003.
Size Group
(mm SL) Nt
% of Total DensityT
Immature
<70
28
59.57
0.055 (0.032)
~70
19
40.43
0.037 (0.014)
Mature
Pre-Recruit
92-99
3
6.38
0.006 (0.003)
New Recruit
100-106
2
4.25
0.004 (0.004)
~1 00
2
4.25
0.004 (0.004)
Legal
Total
47
100.00
0.092 (0.038)
f Number of Abalone f Values in Brackets are standard errors
Shell
Length:!:
41.9 (3.0)
81.8 (1.2)
96.3 (1.5)
100.5 (0.5)
100.5 (0.5)
59.1 (3.7)
10
PFMA
27 & 127
128"l5'
Figure 1. Map of abalone survey area, north-west coast of Vancouver Island.
11
4-.--------------------------,
3
CD
C
o
fti
.02
«
....
o
:tI:
1
o
10
20
30
40 50 60 70 80
Shell Diameter (mm)
90
100 11 0
Figure 2. Size frequencies of exposed abalone for all transects surveyed on the north­
west coast of Vancouver Island, May 2003.
18
16
14
Q)
c 12
0
ca 10
.0
<C
8
0
6
:t:I:
4
2
0
0
1
2
3
4
5
6
7
Depth (m)
Figure 3. Abalone counts by depth for all transects surveyed on the north-west coast of
Vancouver Island, May 2003.
12
7--.-------------------------.
6
5
Q)
c
.24
ca
.c
~3
o
=It:
2
1
O-t--t--t--t--+--+--+--,'L-+--+­
o
10
20
30 40 50
60 70
Shell Diameter (mm)
80
90
100
Figure 4. Size frequencies of abalone collected for DNA analysis from Quatsino Sound,
north-west Vancouver Island, May 2003.
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