Stevens Survival of king and tanner crabs captured incidentally in the Bering Sea 



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A KING CRAB 



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CD FEMALES 

 ^ MALES 



60 80 100 120 140 160 



CARAPACE LENGTH (mm) 



B TANNER CRAB 



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 ^ MALES 



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40 60 80 100 120 140 



CARAPACE WIDTH (mm) 



Figure I 



Size frequency of crahs caught during the e.xperiment, shown as a 

 moving average of three 1-mm intervals. Numbers are expanded from 

 number measured by sampling factors. Se.xes are stacked. 



Results 



Over 6200 t of fish were sorted through during the 

 study, and over 50000 crabs were recovered and 

 measured (Table 1), the majority being Tanner crabs 

 (which shall be used herein to refer only to the species 

 Chionoecetes bairdi), and the remainder mostly king 

 crabs Paralithodes camtschaticus. A few C. opilio were 

 encountered but are not discussed here. Vitality was 

 coded on over 10 750 crabs, representing 23985 total 

 crabs after expansion by subsampling factors. Injuries 

 were recorded for 3353, and 691 were held in tanks 

 for delayed mortality studies. The size distribution of 

 king crabs was bimodal (Fig. lA); males exhibited 

 modes near 62 and 135 mm CL, and females near 62 

 and 100 mm CL. Both sexes of Tanner crabs exhibited 

 a single mode near 80 mm CW (Fig. IB). 



Overall survival 



Overall survival was 21% ( ± 2.0%) for king crabs, and 

 22% (±3.6%,) for Tanner crabs (Table 2). Results for 

 Tanner crabs are less accurate because fewer crabs 

 were retained, especially from vitality gi'oup 1. Virtual- 

 ly no crabs were recorded as moribund after holding 

 in live-tanks, regardless of initial condition; crabs either 

 "recovered" or died. Potential sublethal effects, such 

 as reduced feeding or growth rates due to injuries, 

 could not be accounted for. At least one crab which 



