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Canadian Manuscript Report of
Fisheries and Aquatic Sciences 2487
1999
RESURVEY OF ABALONE POPULATIONS AT
TRIBAL GROUP, SIMONDS GROUP AND STRYKER ISLAND,
CENTRAL COAST OF BRITISH COLUMBIA, 1998 by
B.G. Lucas\
A.
Campbell, and K. Cripps
2
Fisheries and Oceans Canada
Science Branch, Pacific Region
Pacific Biological Station
Nanaimo, British Columbia
V9R5K6 lLucas
Research, Sooke, B.C. VOS INO
2Eco-Pacific Resource Management and
Heiltsuk Fisheries Program, Waglisla, B.C.
VOT lZO
11
<0 Minister ofPublic Works and Government Services Canada 1999
Cat. No. Fs97-4/2487E
ISSN 0706-6473
Correct citation for this publication:
Lucas, B.G.,
A.
Campbell, and
K.
Cripps. 1999. Resurvey of abalone populations at Tribal
Group, Simonds Group and Stryker Island, central coast ofBritish Columbia, 1998. Can.
Manuscr. Rep. Fish. Aquat. Sci. 2487: 18 p.
III
ABSTRACT
Lucas, B.G.,
A.
Campbell, and K. Cripps. 1999. Resurvey of abalone populations at Tribal
Group, Simonds Group and Stryker Island, central coast of British Columbia, 1998. Can.
Manuscr. Rep. Fish. Aquat. Sci. 2487: 18 p.
Transect surveys were conducted to determine population size structure and density for northern abalone, Haliotis kamtschatkana, in the Tribal, Simonds and Stryker Island Groups on the central coast of British Columbia during May and June, 1998. Size frequencies and mean shell length (SL) of abalone decreased with depth in all areas. Adult abalone
(~
70 mrn SL) were more abundant in
<
5 m depths, whereas small juveniles
«
50 mrn SL) were found at all depths, but less frequently at intertidal depths. Exposed abalone densities ranged from 0 - 3.58 per m
2
, with a mean for all areas of 0.42 per m
2
.
Mean densities were greater for all size groups in the Tribal
Group than at Stryker Island, and were greater than all size groups except "legal"
(~
100 mrn SL) in the Simonds Group. Comparisons between 1997 and 1998 surveys for all three areas combined indicated that, although mean densities were generally lower in 1998, the differences between the two years were not statistically significant. Persistently low densities of exposed abalone warrant continued concern for the conservation of
H.
kamtschatkana in this area of the central coast of
British Columbia.
IV
Lucas,
RG., A.
Campbell, and K. Cripps. 1999. Resurvey of abalone populations at Tribal
Group, Simonds Group and Stryker Island, central coast ofBritish Columbia, 1998. Can.
Manuscr. Rep. Fish. Aquat. Sci. 2487: 18 p.
Nous avons effectue, en mai et en juin 1998, des releves sur transects pour determiner la structure par taille et la densite des populations d' ormeau nordique (Haliotis kamtschatkana) dans les groupes d'iles Tribal et Simonds, et l'ile Stryker, dans la zone centrale de la cote de Colombie
Britannique. La frequence des tailles et la longueur moyenne de la coquille (LMC) des ormeaux diminuaient en fonction de la profondeur dans toutes les zones. Les ormeaux adultes
(~70 mm
LMC) etaient plus abondants a des profondeurs de moins de 5 m, tandis que les petits juveniles
(<
50 mm LMC) se retrouvaient a toutes les profondeurs, mais moins frequemment dans la zone intertidale. Les densites des ormeaux exondes etaient de 0 a
3,58 au m 2
, avec une moyenne de
0,42 au m 2 dans toutes les zones. Pour toutes les grandeurs, les densites moyennes etaient plus elevees dans les iles Tribal que dans l'ile Stryker; et elles etaient plus elevees pour toutes les grandeurs, sauf pour la taille
« legale »
(~
100 mm LMC), dans les iles Simonds. La comparaison des reieves de 1997 et de 1998 pour les trois zones a montre que, meme si en generalles densites moyennes etaient moins elevees qu'en 1997, les differences entre les deux annees n'etaient pas statistiquement importantes. Les densites des ormeaux exondes restent faibles, et la preservation
d'H. kamtschatkana demeure tres preoccupante dans cette region de la Colombie-Britannique.
INTRODUCTION
The 'northern' or 'pinto' abalone,
Haliotis kamtschatkana, generally occurs in patchy distribution on exposed and semi-exposed coasts from Sitka Island, Alaska to Baja California, including British Columbia (B.C.) (Sloan and Breen 1988). Northern abalone were harvested by first nations, and in commercial and recreational fisheries in B.C. until 1990, when the fishery was closed due to conservation concerns after surveys indicated that the abundance of northern abalone had declined (Wmther et al. 1995; Thomas and Campbell 1996). Abalone stocks in the
Heiltsuk First Nation's traditional fishing area were surveyed during 1980 (Breen and Adkins
1982), 1993 (Thomas and Campbell 1996), and 1997 (Campbell et al. 1998) using the standard, broad-scale survey design established by Breen and Adkins (1979). A random transect method
(Cripps and Campbell 1998) was used to survey abalone populations in the Tribal Group,
Simonds Group, and Stryker Island in 1997 (Campbell and Cripps 1998).
Monitoring abalone populations on a frequent basis (e.g., yearly) can provide time-series trends on abalone population characteristics such as changes in density and recruitment. The objectives of this study were to estimate the density of abalone using the random transect method during 1998, to determine any relationships between depth and abalone size and density, and to compare changes in abalone populations between the 1997 and 1998 transect surveys conducted in the Heiltsuk traditional fishing areas (Fig. 1).
METHODS
The positions of the transects surveyed in this study were approximately the same as those surveyed in 1997 (Campbell and Cripps 1998), with the addition of six new transects. In 1997 and for new transects, transect locations were randomly placed on a nautical chart by positioning a metric ruler, marked in mm, along the length of shoreline to be surveyed. A random numbers table was used to select the position along the ruler where survey transects were to be placed.
For transects previously surveyed, transect origin was located using GPS. The transect survey method (Cripps and Campbell 1998) was used for both studies. The primary sampling unit was a
''transect'', made up of a cluster or variable number of secondary units. Each transect was one meter wide and variable in length, depending on the slope of the substrate, from the intertidal zone to approximately 8 m below chart datum. All depth recordings were converted to depth at datum. The secondary sampling unit consisted of aim x 1 m square quadrat that was place on the right side of the transect line. Lead line was deployed from the transect origin, and perpendicular to the isopleths, to an estimated depth of approximately 8 m. Divers flipped the quadrat parallel to the transect line, from deep to shallow, and the number of "emergent" or
"exposed" (visible on rocks) abalone, shell length (SL in mm) of each abalone, depth, substrate type, and dominant algal cover was recorded for every second quadrat. All kelp, sea urchins and starfish were removed from the quadrat to ensure abalone were easily detectable. However, boulders were not moved to examine for cryptic abalone. Caution was exercised to ensure that
2 abalone in upcoming quadrats were not disturbed. Sampling only exposed abalone is an efficient sampling strategy, since the majority of mature abalone (i.e.,
~
70 mm SL) are exposed (Campbell
1996).
The mean density, d (number/m
2
), was calculated as:
LC i
d=_i_
La j j
The standard error of the mean density, se (d), was calculated as:
(l)
L(c i
-da i
)2 se(d) i
=
1 1 - - - - -
n(n-l)a
2
(2) where for each i th transect,
Cj
= the number of abalone observed in a transect,
~
= the area ofthe transect surveyed (number of quadrats) in square meters, a
= the mean transect area for all transects, n
= the number oftransects sampled, and N
= the total population of possible transects.
This method accounted for the variable length oftransects. Means and standard errors of densities by depth range and abalone size class were also calculated by subsampling each transect.
The depth ranges were (1) < 0 m, (2) 0 - 1.50 m, (3) 1.51 - 3.00 m, (4) 3.01 - 4.50 m, (5) 4.51
6.00 m,
(6) 6.01 - 7.50 m and (7)
>
7.50 m. The size classes were "small juveniles" 10 - 49 mm
SL, "large juveniles" 50 - 69 mm SL, "mature"
~
70 mm SL [i.e., about 100
% of abalone would be mature (Campbell et al. 1992)], "prerecruit" 92 - 99 mm SL, "legal"
~
100 mm SL, "new recruit" 100 - 106 mm SL and "total" which included all sizes. Although some of the size categories overlap, they were included in the analyses so that the results could be compared with previous surveys of abalone from these and other areas. The number of abalone measured for SL at one site did not match the number of abalone recorded by divers, because two individuals were not accessible. Consequently, densities by size category (Oi) were calculated as:
Di
= PiD
(3) where the proportion of abalone in each size category
(Pi
= the number per category i divided by the total abalone measured in the sample) was multiplied by the total density of abalone
(0) counted by divers from all quadrats at that site (Campbell et al. 1998).
RESULTS
SURVEY LOGISTICS SUMMARY
The number of transects surveyed offthe Tribal Group was 30, the Simonds Group was
32, and Stryker Island was 28 (Tables 1,2). The mean length oftransect was 24.8 m for the
Tribal Group, 34.3 m for the Simonds Group, and 36.5 m for Stryker Island.
3
POPULATION SIZE STRUCTURE
Small juvenile exposed abalone
50 mm SL) made up 41.5 %, 24.8 % and 25.2 % of the population for Tribal Group, Simonds Group and Stryker Island, respectively. The length frequency distribution of exposed abalone indicated that the majority (> 85%) of animals sampled at all locations were
<
100 mm SL (Fig. 2, Table 3). The number ofjuvenile abalone found probably does not accurately reflect the true proportion ofjuveniles because of the difficulty of detecting small juvenile individuals, which prefer cryptic habitats (Sloan and Breen 1998). Adult abalone
(~70 mm SL) were 41.2 %,50.5 % and 38.1 % of the population for Tribal Group,
Simonds Group and Stryker Island, respectively. The percentage of legal abalone
(~
100 mm SL) was greater for the Simonds Group (14.6 %) than for the Tribal Group (7.8 %) and for Stryker
Island (6.1 %).
Size frequencies and mean SL of abalone generally decreased as depth increased (Figs.
3A, 3B, 3C, 4). Adult abalone were more abundant
<
5 m depths, whereas small juveniles
50 mm SL) were found at all depths, but less frequently at intertidal depths (Figs. 3A, 3B, 3C).
DENSITY ESTIMATES
Comparison between areas
Mean densities per transect ranged from 0 to 3.58 total exposed abalone per m
2
(Table 1,
Fig. 5). Total mean densities of abalone of different size groups for all depths were greater for the
Tribal Group than those at Stryker Island, and were greater for all size groups except "legal"
(~100 mm SL) than those in the Simonds Group during 1998 (Table 4). Abalone densities were generally highest in depths
<
3 m, although abalone were found at all depths surveyed (Fig. 6).
Comparison between 1997 and 1998
For all areas combined, there were no statistically significant differences in mean density estimates for any size group of abalone between 1997 and 1998, despite decreases in mean density for most size groups (Table 4). However, in the Tribal Group, mean density estimates increased between 1997 and 1998 for all size groups of abalone, except large juveniles (50 - 69 mm SL). There were significant increases in total abalone (33 %; Wllcoxon signed rank test, p
=
0.049) and in mature abalone (29%; Wllcoxon signed rank test, p
=
0.042) between 1997 and
1998 in the Tribal Group (Table 4). In the Simonds Group, mean density estimates decreased between 1997 and 1998 for all size groups of abalone, although the differences were not statistically significant except for prerecruit densities (61% decrease; Wilcoxon signed rank test, p
=
0.041). At Stryker Island, although mean density estimates generally decreased between 1997 and 1998 for all size groups of abalone, the differences were not statistically significant (Table 4).
4
DISCUSSION
This study showed that mean size and density of abalone varied with depth. Most exposed abalone in these areas were smaller than "legal" size «100 mm SL). Small abalone were distributed throughout the surveyed depth range (-1 - 11 m), but larger animals were more likely to be found in the 0 - 3 m depth range. Mean abalone size and density declined with depth, as in previously reported studies (Sloan and Breen 1988; Campbell and Cripps 1998; Cripps and
Campbell 1998). This trend is probably caused by adult abalone preferences for shallow water for spawning (Breen and Adkins 1980; Campbell and Cripps 1998). Although previous studies reported juvenile
H.
kamtschatkana were generally found deeper than adults (Breen and Adkins
1979, 1982; Sloan and Breen 1988), this study suggested that juveniles were evenly distributed throughout all subtidal depths.
Considerable variation was found in mean abalone densities between areas and between transects within areas. Northern abalone distributions are known to be patchy, due to their aggregating behaviour (Sloan and Breen 1988).
In general, densities were not significantly different between the 1997 and 1998 surveys.
Although the mean density for all areas combined decreased between May 1997 and May 1998, mean density increased in the Tribal Group and decreased in the Simonds Group and Stryker
Island during the same period. This difference between areas may be caused by variations in environmental factors, natural mortality, disease, predation, or illegal harvesting. The significant increases in estimated densities of total
(0.468/m
2
to
0.659/m
2
)
and mature (0.
188/m
2
to 0.271/m
2
) abalone in the Tribal Group represent a change in only a small number of abalone. The increase in total abalone may be primarily due to small juveniles that were too small to detect during the previous survey. The increase in mature abalone may be due to growth of large juveniles. Some differences may also arise from minor variations in transect origins caused by GPS imprecision.
The proportion of mature abalone in all areas was lower in 1998 than in 1997.
The estimated mean total density, for all areas combined, of exposed abalone found in this study
(0.420/m
2
)
appears to be similar to the densities found in previous surveys of abalone on the central coast. Using the same transect method, similar densities were found at Dallain Point and
Higgins Pass (O.391/m
2 and
0.429/m
2
,
respectively) (Cripps and Campbell 1998). Slightly higher densities were found using the "Breen" method (Breen and Adkins 1979) in the central coast in
1993 (O.53/m
2
)
(Thomas and Campbell 1996), and in 1997
(0.44/m
2
)
(Campbell et al. 1998). The
"Breen" method tends to give higher density estimates because the survey is limited to depth ranges where abalone are naturally more abundant (Campbell et al. 1998).
This survey showed abalone population densities continue to be low, despite closure of the fishery since 1990. Although the decreases in density observed in this study for all areas combined are not statistically significant, the densities of exposed prerecruit and new recruit abalone
(O.026/m
2
and
0.020/m
2
,
respectively) are still well below recommended replacement levels
(O.55/m
2
and
0.45/m
2
,
respectively) (Breen 1986). More research to determine growth, mortality, and recruitment rates is required to accurately estimate abalone productivity and the
5 ability of abalone populations to recover from previous exploitation. Consequently, there still remain conservation concerns for
H.
kamtschatkana along the central coast ofB.C.
ACKNOWLEDGMENTS
We thank S. Humchitt, V Jackson, and D. Reid for conducting the dive surveys, L. Barton for assisting with the chart-figure preparation, the Heiltsuk Band Council and the Aboriginal
Fisheries Strategy for funds and logistic support for the surveys, Fisheries and Oceans Canada for providing a science and technology internship to B. G. Lucas, and
I.
Wmther for reviewing this paper.
REFERENCES CITED
Breen, P.A 1986. Management ofthe British Columbia fishery for northern abalone
(Haliotis
kamtschatkana). Can. Spec. Publ. Fish. Aquat. Sci. 92: 300 - 312.
Breen, P.A and B.E. Adkins. 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.
Breen,P.A and B.E. Adkins. 1980. Spawning in a British Columbia population of northern abalone, Haliotis kamtschatkana. Veliger 23: 177 - 179.
Breen, P.A and RE. Adkins. 1982. Observations of abalone populations on the north coast of
British Columbia, July 1980. Can. Manuscr. Rep. Fish. Aquat. Sci. 1633: 55 p.
Campbell, A 1996. An evaluation of abalone surveys off southeast Queen Charlotte Islands.
Can. Tech. Rep. Fish. Aquat. Sci. 2089: 111 - 121.
Campbell, A and K. Cripps. 1998. Survey of abalone populations at Stryker Island, Tribal
Group and Simonds Group, central coast ofBritish Columbia, May, 1997. Can. Manuscr.
Rep. Fish. Aquat. Sci. 2451: 21 p.
Campbell, A,
I.
Manley, and W. Carolsfeld. 1992. Size at maturity and fecundity of the abalone,
Haliotis kamtschatkana, in northern British Columbia. Can. Manuscr. Rep. Fish. Aquat.
Sci. 2169: 47 - 65.
Campbell, A,
I.
Winther, R Adkins, D. Brouwer, and D. Miller. 1998. Survey of the northern abalone (Haliotis kamtschatkana) in the central coast ofBritish Columbia, May 1997.
Pacific Stock Assessment Review Committee Working Paper 198-4, 30 p.
6
Cripps, K. and A Campbell. 1998. Survey of abalone populations at Dallain Point and Higgins
Pass, central coast ofBritish Columbia, 1995 - 96. Can. Manuscr. Rep. Fish. Aquat. Sci.
2445: 31 p.
Sloan, N.A and P.A Breen. 1988. Northern abalone,
Haliotis /camtschatkana,
in
British
Columbia: fisheries and synopsis of life history information. Can. Spec. Publ. Fish.
Aquat. Sci. 103: 46 p.
Thomas, G. and A Campbell. 1996. Abalone resurvey in
Aristazabal Island, the Estevan Group and Banks Island, June 1993. Can. Tech. Rep. Fish. Aquat. Sci. 2089: 97 - 109.
Winther, I., A Campbell, G.A Thomas, RE. Adkins, and RG. Clapp. 1995. Abalone resurvey in the southeast Queen Charlotte Islands, 1994. Can. Manuscr. Rep. Fish. Aquat. Sci.
2273: 46 p.
7
Table 1. Dive survey summary for abalone transects surveyed in the Tribal Group, Simonds Group and Stryker Island, during May and June 1998.
206
207
208
209
210
211
212
213
214
215
Transect Date
Tribal Group
101 May-29
102
103
105
May-29
May-29
May-29
106
107
108
109
110
111
112
113
May-29
May-30
May-30
May-29
May-29
May-30
May-29
May-29
114
115
116
117
118
119
120
121
122
123
124
125
126
May-30
May-30
May-30
May-30
May-31
May-31
May-31
May-31
May-31
May-31
May-31
May-30
May-31
127
128
201
202
203
May-30
May-30
129
130
131
May-31
May-31
May-30
Simonds Group
Jun-4
Jun-3
204
205
Jun-3
Jun-3
Jun-3
Jun-3
Jun-3
Jun-3
Jun-1
Jun-1
Jun-1
Jun-1
Jun-1
Jun-1
Jun-4
Time
Start Finish
11:25
11:06
13:51
13:26
13:07
12:36
12:14
11:40
11:28
15:30
9:55
14:42
14:00
10:34
10:54
9:42
11:49
12:06
12:38
13:05
13:33
10:31
10:04
14:00
14:27
10:50
15:18
15:02
13:12
11:25
11:57
12:30
12:55
13:25
13:45
10:42
10:23
14:21
14:54
11:02
15:27
15:08
13:30
11:35
11:35
11:15
14:13
13:43
13:20
12:55
12:31
12:03
11:45
15:48
10:23
15:23
14:36
10:45
11:17
9:56
9:34
13:24
13:48
17:53
17:14
16:51
16:07
16:28
12:15
11:40
11:20
10:49
10:01
16:05
11:29
9:59
13:37
14:16
18:21
17:45
17:04
16:20
16:42
12:35
12:06
11:31
11:12
10:39
16:38
11:42
Bottom
Time
0:25
0:13
0:28
0:28
0:31
0:13
0:13
0:14
0:20
0:26
0:11
0:23
0:38
0:33
0:13
0:08
0:24
0:17
0:20
0:12
0:11
0:19
0:21
0:27
0:12
0:09
0:06
0:18
0:10
0:10
0:09
0:22
0:17
0:13
0:19
0:17
0:23
0:17
0:18
0:28
0:41
0:36
0:11
0:23
0:14
Depth (m)
Min Max
Number of Total # Density
Quadrats of Abalone (No.lm2)
0.79
-0.61
0.09
-0.58
-0.21
-0.73
-0.58
-1.34
-0.61
-0.88
-0.73
-0.18
-0.91
-0.09
-0.40
-0.18
-1.10
-0.03
-0.30
-0.88
-0.64
-1.07
-1.19
-2.47
-1.86
-0.67
0.85
-1.34
-1.07
-0.88
-1.43
-2.16
-1.01
-0.98
-1.31
-1.10
-1.28
-1.31
-0.82
-1.65
-1.89
-1.58
1.65
-1.13
-2.13
10.58
10.52
9.69
9.11
9.08
9.54
10.85
9.63
8.63
9.72
7.89
8.14
9.88
10.24
10.24
9.81
9.69
9.75
9.78
9.72
9.66
9.75
8.47
6.83
9.11
10.21
10.09
8.90
9.08
9.94
8.38
8.44
9.81
8.69
8.93
9.02
9.11
9.08
9.08
8.84
8.69
7.83
8.05
8.63
8.53
6
9
9
13
9
10
15
14
19
12
10
13
11
8
8
11
17
11
14
16
12
9
20
9
19
12
16
8
13
16
19
13
35
25
43
13
12
11
15
19
9
22
29
20
10
0.09
0.24
0.27
0.00
0.13
0.25
0.67
0.20
0.56
0.63
3.58
1.06
0.88
0.62
0.44
1.14
1.37
0.33
0.00
0.00
0.18
0.75
0.13
0.17
2.56
1.67
0.77
0.22
1.00
0.33
0
2
6
1
1
16
26
4
0
1
23
15
10
2
10
5
4
3
0
2
3
6
4
5
12
43
17
7
8
7
13
9
19
7
4
5
12
7
9
4
2
6
1
18
4
0.68
0.69
0.54
0.28
0.09
0.38
1.00
0.64
0.60
0.21
0.22
0.27
0.03
0.90
0.40
8
Table 1 (cont'd)
Time
Transect Date
Simonds Group (cont'd) start Finish
216 Jun-4 11:14 11:23
217
218
219
220
221
222
223
Jun-4
Jun-4
Jun-3
Jun-3
Jun-3
Jun-2
Jun-2
10:54
9:00
11:46
12:50
11:26
13:46
13:06
11:05
9:24
12:08
13:07
11:40
14:08
224
225
229
230
231
232
Jun-2
Jun-1
Jun-2
Jun-1
Jun-1
Jun-1
12:28
11:52
10:44
14:32
13:11
13:36
12:57
12:19
11:05
15:07
13:31
15:36
15:54
11:49
10:11
15:50
15:59
12:04
10:46
233
234
235
Jun-1
Jun-4
Jun-4
Stryker Island
301
May-28
302
303
304
May-28
May-28
May-28
305
306
307
308
309
May-28
May-27
May-26
May-26
May-26
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
May-26
May-26
May-26
May-26
May-26
May-26
May-27
May-27
May-27
May-28
May-27
May-27
May-27
May-27
May-27
May-27
May-26
May-27
May-27
9:38
9:57
11:23
10:19
10:46
14:30
14:57
13:45
14:04
13:18
12:52
12:00
11:00
10:23
9:56
10:38
10:05
11:03
13:04
11:25
11:50
12:11
12:42
13:02
13:28
11:28
13:52
9:43
9:49
10:08
11:30
10:35
11:17
14:53
15:07
13:55
14:37
13:35
13:10
12:42
11:16
10:46
10:11
10:54
10:30
11:15
13:27
11:41
12:01
12:37
12:53
13:17
13:43
11:50
14:16
9:58
Bottom
Time
0:30
0:29
0:27
0:21
0:35
0:20
0:14
0:09
0:11
0:24
0:22
0:17
0:14
0:22
0:05
0:15
0:35
0:33
0:17
0:18
0:42
0:16
0:23
0:15
0:16
0:25
0:12
0:23
0:16
0:11
0:26
0:11
0:11
0:07
0:16
0:31
0:23
0:10
0:10
0:11
0:15
0:15
0:22
0:24
0:15
Depth (m)
Min
0.09
-0.40
0.00
1.52
0.18
1.01
-0.58
-0.21
-0.21
-0.49
-0.76
-0.85
0.24
-0.46
-0.82
0.58
0.30
0.40
-0.34
0.15
-0.24
0.27
-0.18
0.34
0.27
0.27
-1.80
0.18
-0.43
-1.55
0.46
-1.34
-0.30
-1.62
-1.68
-1.77
-1.52
-0.61
-1.52
-1.92
-0.55
-2.35
-2.19
-1.40
-1.65
Max
8.84
8.53
8.84
8.20
8.53
8.72
9.08
8.84
9.17
8.93
9.17
9.48
10.00
9.78
9.02
8.56
8.60
10.27
10.39
10.39
10.49
10.52
7.22
6.55
7.16
6.95
7.53
7.92
8.81
9.78
8.72
10.79
9.88
9.11
9.39
10.76
9.75
9.72
9.39
8.87
8.53
8.11
9.36
7.74
9.11
Number of Total # Density
Quadrats of Abalone (No.lm2)
8
14
14
11
13
8
12
28
22
17
11
19
10
9
8
11
39
10
12
7
31
32
29
15
6
36
18
15
24
12
18
9
15
47
7
15
8
7
35
13
10
20
16
26
12
2
1
2
6
5
0
10
11
5
3
3
14
8
1
0
6
9
0.25
0.07
0.14
0.55
0.38
0.00
0.83
0.39
0.23
0.18
0.27
0.74
0.80
0.11
0.00
0.55
0.23
6
6
5
0
3
7
5
15
6
4
7
2
13
1
11
2
0
3
6
4
13
7
3
12
3
4
0
1
0.00
0.25
0.39
0.56
0.40
0.13
0.71
1.00
0.75
0.57
0.20
0.15
1.30
0.05
0.69
0.08
0.00
0.30
0.33
0.00
0.03
0.41
0.24
0.20
2.00
0.08
0.33
0.27
9
Table 2. Summary statistics of transect survey of exposed abalone from Tribal Group, Simonds Group and Stryker Island during May and June
1998.
Values in brackets are standard errors.
Details per transect
Dates
Number of transects
Mean transect length (m)
Mean depth (m)
Mean number of quadrats
Mean minutesllransect
Mean minutes/quadrat
Tribal Group
May 29 - 31
30
24.80
4.07 (0.17)
12.30 (0.67)
17.72 (1.48)
1.44 (0.42)
Simonds Group
June 1 - 4
32
34.25
3.87 (0.13)
17.16 (1.62)
21.20 (1.53)
1.24 (0.3D stryker Island
May
26- 28
28
36.46
4.45 (0.13)
18.04 (2.00)
18.34 (1.52)
1.02 (0.36)
Table
3.
Mean shell length (mm SL) of exposed abalone of different size groups for all transect surveys of the Tribal Group. Simonds Group and Stryker Island during May and June 1998. N = number of abalone. Values in brackets are standard errors.
Size Group
Tribal Group
Mature
Pre Recruit
New Recruit
Legal
Simonds Group
Mature
Pre Recruit
New Recruit
Legal
Stryker Island
Mature
Pre Recruit
New Recruit
Legal
(mm SLl
>=70
92-99
100 -106
>= 100 all sizes
>=70
92 -99
100 -106
>= 100 all sizes
>=70
92 -99
100 -106
>= 100 all sizes
N
100
17
15
19
243
104
14
10
30
206
56
6
4
9
147
% of Total
41.2
7.0
6.2
7.8
100.0
50.5
6.8
4.9
14.6
100.0
38.1
4.1
2.7
6.1
100.0
Shell Length
87.5 (1.1)
95.1 (0.5)
102.7 (0.5)
104.8 (1.1)
57.9 (1.9)
91.2 (1.4)
95.6 (0.7)
102.8 (0.6)
110.0 (1.2)
69.3 (1.9)
85.0 (1.6)
94.5 (1.2)
102.0 (1.2)
106.3 (1.8)
62.8 (1.8)
10
Table 4. Mean density (number/m
2
) of exposed abalone of different size groups for all depths from
Tribal Group, Simonds Group and Stryker Islands during 1997 and 1998. Values in brackets are standard errors. Means of densities from different years followed by the same letter, in the same row, are not significantly different (Wilcoxon signed rank test, a
=
.05, P
>
0.05). Means followed by different letters, in the same row, are significantly different (Wilcoxon signed rank test, a
=
0.05, P
~
0.05).
Area
All areas
Size Group
Small Juveniles
Large Juveniles
Mature
Pre Recruit
New Recruit
Legal
Total
Transects
Tribal Group
Simonds Group
Small Juveniles
Large Juveniles
Mature
Pre Recruit
New Recruit
Legal
Total
Transects
Small Juveniles
Large Juveniles
Mature
Pre Recruit
New Recruit
Legal
Total
Transects
Stryker Island
Small Juveniles
Large Juveniles
Mature
Pre Recruit
New Recruit
Legal
Total
Transects mmSL
10-49
50-69
>=70
92- 99
100 -106
>= 100 all sizes
10-49
50-69
>=70
92- 99
100 -106
>= 100 all sizes
10 -49
50-69
>= 70
92- 99
100 -106
>= 100 all sizes
10 -49
50-69
>= 70
92- 99
100 -106
>= 100 all sizes
1997
0.112 (0.021)a
0.134 (0.021)a
0.258 (0.045)a
0.044 (0.010)a
0.025 (0.008)a
0.050 (0.019)a
0.520 (0.060)a
81
0.115 (0.029)a
0.167 (0.042)a
0.210 (0.051)a
0.037 (0.012)a
0.006 (O.OO4)a
0.011 (O.OO7)a
0.494 (0.089)a
29
0.107 (0.028)a
0.124 (0.032)a
0.289 (0.079)a
0.056 (0.019)a
0.040 (0.018)a
0.094 (0.041)a
0.536 (0.086)a
32
0.119 (0.062)a
0.106 (0.029)a
0.272 (0.103)a
0.034 (0.016)a
0.025 (0.012)a
0.029 (0.015)a
0.528 (0.156)a
20
1998
0.128 (0.029)a
0.104 (0.014)a
0.183 (0.022)a
0.026 (O.006)a
0.020 (O.006)a
0.041 (0.009)a
0.420 (0.049)a
90
0.257 (0.101)a
0.117 (0.030)a
0.271 (0.051)b
0.046 (0.014)a
0.041 (0.018)a
0.051 (0.020)a
0.659 (0.138)b
30
0.091 (0.020)a
0.093 (0.019)a
0.189 (0.039)a
0.022 (0.009)b
0.018 (O.OO7)a
0.055 (0.017)a
0.375 (0.051)a
32
0.076 (0.023)a
0.108 (0.029)a
0.111 (0.020)a
0.016 (O.OO7)a
0.008 (0.005)a
0.018 (O.OO7)a
0.295 (O.067)a
28
11
128:20
a
C\I
LO
128:30
01
N a
01
N a
01
LO a
C\I
LO
1 a a
C\I
LO
01
~ a a
.~
•
~.,~
I
~!~/J
~~
'-
(/'
01
01
-
01
LO
..
LO
2
:
o
:
2700 5400 8100 10800 13500
128:30 128:20
Figure 1. General location of study areas (1) Tribal Group (in statistical area 7 - 18), (2)
Simonds Group
(in statistical area 7 - 25), and (3) Stryker Island
(in statistical area 7 - 18 and 7
19), in the central coast of British Columbia surveyed for abalone during May and June 1998.
12
C
::I o o
15
....-------r---~-----.0.06
A
MEAN
=
58
0.05
N =243
10
0.04
""0
.g o
0.03
0.02
:::I.
~r
-a
....
~
....
0.01
50
.........-----'0.0
100
SHELL LENGTH (M)
150
C
5
0
1 5 . - - - -......------,.----...,
0.07
B MEAN
=
69
0.06
N =206
10
0.05
0.04
""0
(3
-a o a: o
::I
0.03
0.02
(II
~
0.01
100
.-a..._.....J0.0
50
SHELL LENGTH (M)
150
3
... l::
::I o o
15 ....-------r---,.....-----:::I0.1 0 c
MEAN
=
63
N
=
147
0.08
10
5
0.06
0.04 o
-a g. o·
::I
-a
~
(II
0.02
50 100
.....1...-----'0.0
SHELL LENGTH (M)
150
Figure 2. Size frequencies of exposed abalone from (A) Tribal Group,
(B)
Simonds Group, and
(C) Stryker Island surveyed during May and June, 1998.
13
Figure 3A. Size frequencies by depth category of exposed abalone from the Tribal Group, surveyed during May 1998. Depth category
(1) < 0 m,
(2) 0 - 1.50 m,
(3) 1.51 - 3.00 m,
(4)
3.01 - 4.50 m, (5) 4.51 - 6.00 m, (6) 6.01 -7.50 m and (7) > 7.50 m.
14
1
2
7.-----,--~-____,
6
1
0.16
0.1.
5
0.12
0.10
0.08
0.06 i i
~
O.a.
0.02
L.......LL----lO.O
150
4
5
7,....--.....,...---r--__.0.3
6
4
2
5
2
7,....--.....,...---r-----,
6
2
0.10
0.
08
"II
1
:>
0.06
O.a.
"i i
0.02
50 100
SHELL lENGTH (101)
0.0
150
5
5
6
7.------..---r-----.
5
0.2
3
7.-------..---r------,0.2
2
0.1
0' L...JL..L1. o
50
LJU....LL.L----J 0.0
100 150
SHEll lENGTH (101)
6
7 ' . - - -..........
--~-~0.5
6
6
5
0.•
~
0.3}
2
0.21
If
0.1
:> i
1
If
SHEll LENGTH (101)
7
7,....---,---r------,1.0
7
0.9
6
0.8
5
2
07l
0.6 it
0.5
:>
0.41
0.3
If
02
0.1
1~L.....LIL.L....L5O--...J100L..----Jlsll·0
SHEll lENGTH (101)
Figure 3B. Size frequencies by depth category of exposed abalone from the Simonds Group, surveyed during and June 1998. Depth category (1)
<
0 m,
(2) 0 - 1.50 m,
(3) 1.51 - 3.00 m,
(4)
3.01 - 4.50 m, (5) 4.51 - 6.00 m, (6) 6.01 -7.50 m and (7) > 7.50 m.
15
1
~
S
3
4
2
7
6
1
5
0
0
7
~
S
3
4
2
6
5
4
I
50 100
SHEll lENGTH (101)
4
0
0
1:
:J
8
4
3
2
7
6
5
7
50 100
SHEll lENGTH (101)
7
50 100
SHEll lENGTH (101)
1.0
0.9
0.8
0.7
~
0.6}
0.5
0.41
0.3 r
0.2
0.1
0.0
150
7
6
4}
:J
31 d'
0
150
1: 4
:J
8
3
2
7
6
5
2
0
0
0.3
"
0.21l
~
0.1
1
W
1:
:J
8
4
3
2
7
6
5
5
2
50 100
SHEll LENGTH (101)
5
3
0.12
0.10
0.08
0.06
1 i i'
0.04
~
:J
8
4
3
5
2
6
7
0.02
0.0
150
0
0
3
50 100
SHEll LENGTH (Iol)
6
0.5
0.4
~
0.3 }
0.21 i'
0.1
~
S
3
4
2
6
5
7
6
0.0
150
0.0
150
0
0
50
100
SHEll LENGTH (101)
50 100
SHEll lENGTH (101)
1.0
0.8
0.6
~
1l
~
0.4
1 r
0.2
0.0
150
0.16
0.14
0.12 "
Cl
0.10 1l
0.08
~
0.06 i i
0.04
0.02
0.0
150
Figure 3C. Size frequencies by depth category of exposed abalone from Stryker Island, surveyed during May 1998. Depth category (1) < 0 m, (2) 0 - 1.50 m, (3) 1.51 - 3.00 m, (4) 3.01 - 4.50 m, (5) 4.51 - 6.00 m, (6) 6.01 -7.50 m and (7)
>
7.50 m.
16
100
..........
~
~
'-""
C>
Z
W
.....J
.....J
.....J
w
en
z cd:: w
~
80
60
40
20
Q
~ ~
SIMONDS o.
• 0 .••• -
0.....
TRIBAL
0
-1
. STRYKER
.0.
-£J
\
\
\
~
1 3 5
7 9
Figure 4. Mean shell length of exposed abalone by mean depth in the Tribal Group, Simonds
Group, and Stryker Island during May and June, 1998. Mean depth shown for each of seven depth categories (1)
<
0 m,
(2) 0 - 1.50 m,
(3) 1.51 - 3.00 m,
(4) 3.01 - 4.50 m,
(5) 4.51 - 6.00 m,
(6) 6.01 -7.50 m and (7)
>
7.50 m.
17
... c
::J
0
()
6
10
8
A
MEAN
=
0.66
N =30
0.3
0.2
0
"0 g. o·
::J
"0
..,
0.1 lD
..,
10
B
8
... c
::J
0
()
6
4
MEAN
=
0.38
N =32
0.3
2 o o
1
QO
2 3 4
MEAN ABALONE DENSITY PER TRANSECT
0.2.g
0
;::l o·
::J
"0
..,
0.1 lD
..,
.-.......J .L...
- - - L _......
....J
0.0 o
1 2 3 4
MEAN ABALONE DENSITY PER TRANSECT
3
... c
::J
0
()
6
4
10
8
C
MEAN
=
0.30
N =28
0.3
0.2
0
"0
0 a:
0
::J
0.1
"0
.., lD
!!!
2 o o
1
0.0
2 3 4
MEAN ABALONE DENSITY PER TRANSECT
Figure 5. Frequency distribution of mean densities (number per m
2
) of exposed abalone per transect for all depths combined from (A) Tribal Group,
(B)
Simonds Group, and (C) Stryker
Island surveyed during May and June, 1998.
18
~ lu
::::i: d
II)
2,----,--....-----.-----.-----,
A
27 lRlBAl
AlL
~
::::i:
It:: w
~ z i
1
26
28 28
29 o
'---_...L..-_--'-JL....----J....JL....-....LJ..._----'
-1 3 5 7
9
MEAN DEPTH (M)
~ lu
::::i: d
II)
2...---.----.----,-----.-----,
B
SIMQIIDS
AlL
~
::::i:
It:: w
~ z i
1
0 ' - - - - - ' - - - - - ' - - - - - ' - -...........-
-1 3 5 7
MEAN DEPTH (M)
.......
9
2...---.----.----,-----.-----,
C
SlRYKER
AlL
3 5
MEAN DEPTH (M)
7 9 w
It:: lu
::::i: d
II)
2,----,----.----....-----,----,
D lRlBAl
MATURE
~
It:: w
~ z i
1
27 o
~ ~
L-_L-_...L.l_-===="bI.,._-IJ
-1 3 5 7 9
MEAN DEPTH (M) w
It:: lu
::::i: d
II)
2...---.----.----,-----.-----,
E
SIMQIIDS
MATURE
It:: w
~
::::i:
0.. w z i
1
32 32
0
L-_L-_---L-=------E=:bb_.:L..J
4 3 5 7 9
MEAN DEPTH (M)
2 r.- - - - , - - - - - , - - - - - - , . . . - - - , - - - - - , w
It:: lu
::::i: d
II)
F
SlRYKER
MATURE
It:: w
~ z
~ i
1 o
LL_L-_L..:.::::::E::=::3t=~
4 3 5 7 9
MEAN DEPTH (M) w
It:: lu
::::i: d
II)
2,-----,----.---,----.-----,
G lRlBAl
LEGAL
0.. w
~
<
~
::::i:
It:: w
1
27
28
O'-'-----'-'------.........
..::..:....--L...I-=:...--'-'------IJ
4 3 5 7 9
MEAN DEPTH (M) w
~
::::i: d
II)
2 ...---..-----.------.------.------,
H
SIMQt-.DS lEGAL
It:: w
~
~
; 1 o
3 1 3 1 3 0 3 2 3 2 lL-_.L.-~=6="'=di=......;u....__=LJ
-1 1 3 5 7 9
MEAN DEPTH (M) w
~
::::i: d
II)
2 ,----.------.-----,-----,----,
I
SlRYKER
LEGAL
<
~
::::i:
It:: w
~ z
~
1 o
114 ....25
~27
-1 1 3
26 25 26 2<
5
7 9
MEAN DEPTH (M)
Figure 6. Mean densities of exposed abalone by size group and depth from the Tribal Group,
Simonds Group and Stryker Island, respectively for (A, B, C) all sizes,
(0,
E, F) mature sizes
(~
70 mm SL), and (G, H, I) legal sizes
(~
100 mm SL) surveyed during May and June 1998.
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