Interactions Among Marine Birds and Commercial 

 Fish in the Eastern Bering Sea 



by 



Richard R. Straty and Richard E. Haight 



National Marine Fisheries Service 



Auke Bay Fisheries Laboratory 



Auke Bay, Alaska 99821 



Abstract 



The high primary and secondary productivity of the eastern Bering Sea makes 

 it one of the greatest producers of commercial fish and largest congregating 

 areas of marine birds in the world. The fish and birds are so interrelated that fluc- 

 tuations in the abundance of one may well be responsible for changes in the abun- 

 dance of the other. The seasonal and annual variation in the impact of birds on 

 fish is a function of the life history, food habits, growth rate, and final size of the 

 fish species of concern and of the distribution, abundance, and feeding habits of 

 bird populations plus the effects of the environment on these factors. Stages in 

 the life history of some of the important commercial fish and shellfish of the 

 Bering Sea directly or indirectly influenced by marine birds are identified. 



The eastern Bering Sea is one of the world's 

 richest fish-producing areas and is also one of 

 the world's major congregating areas for 

 marine birds. The large extent of the conti- 

 nental shelf and the climatic and oceano- 

 graphic characteristics of the eastern Bering 

 Sea combine to make this region extremely 

 productive biologically. The distribution and 

 abundance of plankton, benthos, and fish de- 

 termine the distribution, time, and character 

 of the migration of marine birds in the eastern 

 Bering Sea (Shuntov 1961). Several studies 

 have illustrated the close relation between 

 marine birds and the biological properties of 

 surface waters (Tuck 1960; Bourne 1963; Solo- 

 mensen 1965). Spatial and temporal varia- 

 tions in the abundance of the fish families Clu- 

 peidae (herring), Gadidae (codfish), Osmeridae 

 (capelin), and Ammodytidae (sand lance) are 

 thought to be major determinants of the 

 breeding seasons, breeding places, and move- 

 ments of boreal seabirds (Ashmole 1971). The 

 timing of breeding among larids and alcids is 

 related to the seasonal changes in the surface 



waters inhabited by Ammodytidae and Clu- 

 peidae in the North Sea (Pearson 1968). 



The eastern Bering Sea contains members 

 of these and other fish families that are exten- 

 sively exploited by man; the fish are also im- 

 portant as forage for other species of commer- 

 cial fish, marine mammals, and marine birds. 

 During some part of their life cycles, all fish 

 species feed on plankton, nekton, benthos, or 

 other fishes. 



The incidental use or dependence of marine 

 birds on commercial fish and the items on 

 which the fish feed account for the major in- 

 teraction between man and these two groups 

 of animals. 



In this paper, we consider how marine birds 

 and fish interact. Although some of what we 

 present is only speculative, we identify cer- 

 tain areas that have received little or no scien- 

 tific study, areas in which further research is 

 needed for a better understanding of the role 

 of commercial fish in the ecology and dy- 

 namics of marine birds in the eastern Bering 

 Sea. 



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