Resurvey of Abalone Populations at Tribal

Resurvey of Abalone Populations at Tribal

Resurvey of Abalone Populations at Tribal

Group, Simonds Group and Stryker Island,

Central Coast of British Columbia, 1998

B.G. Lucas, A. Campbell, and K. Cripps

Fisheries and Oceans Canada

Science Branch, Pacific Region

Pacific Biological Station

Nanaimo, British Columbia

V9R 5K6

1999

Canadian Manuscript Report of

Fisheries and Aquatic Sciences 2487

1+1

Fisheries and Oceans

Canada

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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

=

.Jl-n/N

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

Campbell

Island

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

Scale in Meters

:

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

SIMONDS GROUP

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

STRYKER ISLAND

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

..........

~

~

'-""

I

C>

Z

W

.....J

.....J

.....J

I

w

en

z cd:: w

~

80

60

40

20

Q

~ ~

SIMONDS o.

• 0 .••• -

0.....

TRIBAL

0

-1

. STRYKER

.0.

-£J

\

\

\

~

1 3 5

MEAN DEPTH (M)

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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