. . . Alaska shellfish Fisheries 



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ISSUES 



High Variability 



These fisheries have been marked by 

 major ups and downs in production (Fig. 

 20-1, 20-2, 20-3) and major perturbations 

 in the shellfish industry. A management 

 policy of maintaining catch stability has 

 evolved, at least for crab stocks. Due to 

 variable survival of young crabs, little can 

 be done to stabilize fluctuations of the crab 

 stocks themselves. Relatively low exploita- 

 tion rates are used to stabilize the annual 

 catch by holding over portions of strong 

 incoming year classes to the next fishing 

 season. This strategy has met with limited 

 success. More effort should be placed on 



the problems of long-term prediction of 

 population changes, of the effect of har- 

 vesting female crabs on population fluctu- 

 ation, and of the effects of discard mortality 

 in pot and trawl fisheries. More study is also 

 required regarding the underlying reasons 

 for shellfish population fluctuations, includ- 

 ing relationships between predator (cod 

 and pollock) and prey (shrimp) abun- 

 dance. Other ecological conditions that 

 lead to strong or weak year classes, such 

 as those influencing larval survival, are 

 also poorly understood. 



Bycatch 



The bycatch of crabs in trawl and pot fish- 

 eries is also a major issue. Mot only is 

 bycatch an allocation problem, the un- 

 known mortalities associated with trawl 

 and pot gear discards of crabs could have 



a biological impact on crab stocks. When 

 crab numbers are low, such bycatch mor- 

 talities, coupled with directed fishing mor- 

 tality, could impose unacceptable risks to 

 stock recovery. 



Lack of Data 



Basic life history information, including 

 growth rates, mortality rates, reproductive 

 cycles, food habits, habitat requirements, 

 and predator-prey relationships, is fre- 

 quently lacking for Alaska shellfish stocks. 

 This is particularly true of the underutilized 

 resources such as mollusks, crangonid 



shrimps, octopuses, squids, sea urchins, 

 and snails. For example, Bering Sea snail 

 stocks represent a latent resource for 

 which markets have existed in the past, but 

 little is known of their numbers, productiv- 

 ity, or potential yield. 



