GUNDERSON: POPULATION BIOLOGY OF SEBASTES ALUTUS 

 '56 '60 '65 '70 



YEAR 



FIGURE 3.— Catch and CPUE data for Pacific ocean perch in 

 Queen Charlotte Sound (from Westrheim et al. 1972). 



operating outside the Canadian fishing zone 

 (Gunderson et al. 1977). 



Both biomass and longevity have been drastic- 

 ally reduced for Pacific ocean perch throughout 

 the Washington-Queen Charlotte Sound region, 

 and it seems unlikely that the current situation 

 will be stable over the long term. The purpose of 

 this study is to outline the population biology of S. 

 alutus stocks in the Washington-Queen Charlotte 

 Sound area and to examine their immediate and 

 long-term response to different harvesting 

 strategies. 



METHODS AND MATERIALS 



Delineation of Stocks 



Two stocks of S. alutus will be examined and 

 contrasted: one in Queen Charlotte Sound (QCS) 

 and one inhabiting the waters off northern 

 Washington and southern Vancouver Island 



(WVI). 



The QCS stock is contained wholly within 

 Queen Charlotte Sound. North of lat. 52°N, the 

 continental shelf off western Graham Island is 

 quite narrow and there is little available habitat 

 for S. alutus. Recent work by Westrheim 3 has 

 shown that previously unexploited stocks exist in 

 Moresby Gully, an undersea canyon extending 

 into Hecate Strait, north of lat. 52°N. The Triangle 

 Islands form a definite southern limit for this 

 stock, since Pacific ocean perch catches im- 

 mediately south of these islands are almost neg- 

 ligible. Pacific Marine Fisheries Commission 

 (PMFC) statistical areas 5 A and 5B offer a con- 

 venient unit for studying this stock. 



The northern limit of the WVI stock lies some- 

 where near the middle of Vancouver Island and, 

 for practical reasons, this was represented by the 

 northern boundary of PMFC area 3C (lat. 49°N). 

 Pacific ocean perch catches in PMFC area 3D have 

 been quite limited historically ( Figure 4), and dur- 

 ing 1966-72, only 13% of the Washington landings 

 in the INPFC Vancouver area came from there 

 (Table 1). 



The southern limit of the WVI stock is more 

 difficult to establish. Since Pacific ocean perch 

 catches by Washington trawlers fall off sharply 

 south of PMFC area 3B-3C (lat. 47°20'N), this was 

 the boundary used throughout this study. This 

 boundary, as well as the others used in this report, 

 is in basic agreement with Snytko (1971), whose 



3 Westrheim, S. J. 1974 Echo-sounder and trawl survey of 

 Queen Charlotte Sound and southern Hecate Strait, 1971-73. 

 Fish. Res. Board Can. Manuscr. Rep. 1307, 43 p. 



55' 



50' 



4 5' 



40° 



140° 130° 



54°30 -/ 



[5C 

 •50"" 



CHARLOTTE % 2 M 



52*00- 



5A 5B 2,804^ 



50° 30' 



30 596" 



VANCOUVER «9'oo'-- 



J6-3C 2,291 

 4 7° 30' 



47-20 



1,079 



COLUMBIA 



44*18' 



2B 488 



43°00 ^™ 



EUREKA |4 



40°30' 



I20°W 



~r 



_L 



55* 



50« 



45° 



40° 



140° 



130° 



120°W 



FIGURE 4. — Chart of the northeastern Pacific Ocean showing 

 INPFC and PMFC statistical areas used in this study. Mean 

 annual Pacific ocean perch catch (metric tons) during 1960-65 

 (heavy lettering) is shown for each PMFC Area. 



371 



