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 Canadian Manuscript Report of Fisheries and Aquatic Sciences Manuscript reports contain scientific and technical information that contributes to existing knowledge but which deals with national or regional problems. Distribution is restricted to institutions or individuals located in particular regions of Canada. However, no restriction is placed on subject matter, and the series reflects the broad interests and policies of the Depamnent of Fisheries and Oceans, namely, fisheries and aquatic sciences. Manuscript reports may be cited as full publications. The correct citation appears above the abstract of each report. Each report is abstracted in Aquatic Sciences and Fisheries Abstracts and indexed in the Depamnent's annual index to scientific and technical publications. Numbers 1-900 in this series were issued as Manuscript Reports (Biological Series) of the Biological Board of Canada, and subsequent to 1937 when the name of the Board was changed by Act of Parliament, as Manuscript Reports (Biological Series) of the Fisheries Research Board of Canada. Numbers 1426 - 1550 were issued as Depamnent of Fisheries and the Environment, Fisheries and Marine Service Manuscript Reports. The current series name was changed with report number 1551. Manuscript reports are produced regionally but are numbered nationally. Requests for individual reports will be filled by the issuing establishment listed on the front cover and title page. Out-of-stock reports will be supplied for a fee by commercial agents. Rapport manuscrit canadien des sciences halieutiques et aquatiques Les rapports manuscrits contiennent des renseignements scientifiques et techniques ques qui constituent une contribution aux connaissances actuelles, mais qui traitent de problemes nationaux ou regionaux. La distribution en est limitee aux organismes et aux personnes de regions particulieres du Canada. II n'y a aucune restriction Quant au sujet; de fait, la serie reflete la vaste gamme des interets et des politiques du ministere des Peches et des Oceans, c'est-A-dire les sciences halieutiques et aquatiques. Les rapports manuscrits peuvent etre cites comme des publications completes. Le titre exact parait au-dessus du resume de chaque rapport. Les rapports manuscrits sont resumes dans la revue Resumes des sciences aquatiques et halieutiques, et ils sont classes dans l'index annual des publications scientifiques et techniques du Ministere. Les numeros 1 A900 de cette serie ont ete publies a titre de manuscrits (serie biologique) de l'Office de biologie du Canada, et apres Ie changement de la designation de cet organisme par decret du Parlement, en 1937, ont ete classes comme manuscrits (serie biologique) de l'Office des recherches sur les pecheries du Canada. Les numeros 901 a 1425 ont ete publies Atitre de rapports manuscrits de l'Office des recherches sur les pecheries du Canada. Les numeros 1426 A1550 sont parus Atitre de rapports manuscrits du Service des peches et de la mer, ministere des Peches et de l'Environnement. Le nom actuel de la serie a ete etabli lors de la parution du numero 1551. Les rapports manuscrits sont produits a l'echelon regional, mais numerotes a l'echelon national. Les demandes de rapports seront satisfaites par l'etablissement auteur dont Ie nom figure sur la couverture et la page du titre. Les rapports epuises seront fournis contre retribution par des agents commerciaux. 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.
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project