Taylor et al.: Snow crab, Chionoecetes opilio, fishery collapse 



415 



CPUE's were derived for research fishing by mul- 

 tiplying the number of commercial crab caught per 

 trap haul by a conversion factor of 0.45 kg/crab (Tay- 

 lor, unpubl. data). Fishermen's logbook catch data 

 were checked against processors' purchase slips. 

 CPUE from logbook data was corrected for the per- 

 centage of sublegal crab in their catch as determined 

 from sampling at processing plants conducted simul- 

 taneously with the research cruises. Total catch re- 

 ported by log/purchase slips was then multiplied by 

 the percentage of legal-sized animals and divided by 

 the reported effort for the same time period to ob- 

 tain a CPUE value comparable to that derived from 

 a coincident research cruise. 



Results 



Logbook data 



Landings and effort data from commer- 

 cial logbooks are summarized in Fig- 

 ure 2. The drop in effort and landings 

 for the Avalon Peninsula in 1980 is the 

 result of a labor dispute and probably 

 does not reflect abundance. Fishery 

 CPUE in both the Avalon and Bonavista 

 Bay areas was at its highest levels dur- 

 ing the spring 1980 at 23.2 kg/trap haul 

 and 11.6 kg/trap haul, respectively (Fig. 

 3). However, off the Avalon Peninsula, 

 catch rates dropped to 19.9 kg/trap haul 

 during the 1981 spring fishery as land- 

 ings peaked at approximately 8500 t. 

 CPUE declined to 13.8 kg/trap haul in 

 1982 despite logbook reports that new 

 commercial fishing grounds were being 

 exploited in the offshore areas ( > 100 km 

 from land). This decline continued, 

 reaching 3.7 kg/trap haul in the spring 

 fishery of 1985 (Fig. 3), a drop of 84% 

 from 1980 levels. This decline in CPUE 

 was accompanied by a dramatic reduc- 

 tion in effort falling from 480,000 trap 

 hauls in 1981 to 17,000 in 1985 (Fig. 2). 

 In comparison, the commercial spring 

 fishery in Bonavista Bay, although over- 

 exploited (Taylor and O'Keefe 4 ), has 

 maintained a comparatively stable level 

 of landings and CPUE since 1981 (905- 

 1805 t and 4.1-to 8.2 kg/trap haul, re- 

 spectively, despite an overall increase 

 in effort from 1980 levels [Fig. 2]). Un- 

 like the Avalon Peninsula fishery, spring 

 catch rates in this area consistently re- 

 flect growth and recruitment into the 

 commercial biomass as newly molted individuals re- 

 cover to commercial acceptability over winter. 



Research cruise CPUE and 

 shell condition data 



Logbook-derived commercial CPUEs and research 

 cruise CPUE data with calculated confidence inter- 

 vals are represented in Figures 3 and 4, respectively. 

 Confidence intervals for most offshore Avalon re- 

 search cruise CPUE data are fairly tight, with the 

 exception of those data from a February 1986 cruise. 



4 Taylor, D. M., and P. G. O'Keefe. 1987. Analysis of the snow 

 crab (Chionoecetes opilio) fishery in Newfoundland for 1986. 



Can. Atl. Fish. Sci. Advis. Comm. 

 Dartmouth, Nova Scotia, 26 p. 



CAFSAC Res. Doc. 87/57, 



