首页 | 本学科首页   官方微博 | 高级检索  
     


A review: Walleye pollock in the North Pacific–how much difference do they really make?
Authors:ALAN M. SPRINGER
Affiliation:Institute of Marine Science University of Alaska Fairbanks, Alaska 99775, U.S.A.
Abstract:Populations of several species of marine birds and mammals in the Bering Sea and Gulf of Alaska have been declining since the mid-1970s, with numbers of one, the Steller sea lion (Eumetopias jubatus) , so depressed it was listed as threatened under the Endangered Species Act in spring 1990. All of the declining populations depend to an important extent on walleye pollock (Theragra chakogramma) for food, although they eat numerous other species as well. In contrast, certain animals that compete with pollock for common prey have been increasing in abundance. All of these changes could be related through food web connections mediated by pollock. Pollock is also important to people–it presently supports the largest single-species commercial fishery in the world, in large part because of its great biomass, which has averaged about 15 × 106t in the Bering Sea over the past 15 years. Pollock consume an inordinate proportion of the pelagic production in the Bering Sea, which further supports the conclusion that it is a key species in the ecosystem. However, there are conflicting hypotheses about the importance of the roles played by pollock as predator and prey, and about the effect that changes in pollock abundance might have on biomass yield at higher trophic levels.
Keywords:walleye pollock    marine mammals    sea-birds    Bering Sea    Gulf of Alaska    ecosystem dynamics    commercial fisheries
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号