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Ecosystem effects of the three capelin stock collapses in the Barents Sea
Gjoesaeter, H; Bogstad, B.; Tjelmeland, S. (2009). Ecosystem effects of the three capelin stock collapses in the Barents Sea. Mar. Biol. Res. 5(1): 40-53. http://dx.doi.org/10.1080/17451000802454866
In: Marine Biology Research. Taylor & Francis: Oslo; Basingstoke. ISSN 1745-1000; e-ISSN 1745-1019, more
Peer reviewed article  

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Keywords
    Aquatic communities > Plankton > Zooplankton
    Aquatic organisms > Marine organisms > Aquatic birds > Marine birds
    Availability > Food availability
    Capelin
    Collapse
    Ecological effects
    Food webs
    Growth rate
    Interspecific relationships > Predation
    Population functions > Recruitment
    Stocks
    Aves [WoRMS]; Phoca groenlandica Erxleben, 1777 [WoRMS]
    Marine/Coastal
Author keywords
    Barents Sea; capelin; ecological effects; stock collapse

Authors  Top 
  • Gjoesaeter, H
  • Bogstad, B., more
  • Tjelmeland, S.

Abstract
    The Barents Sea capelin stock underwent drastic changes in stock size during the last three decades. Three stock collapses occurred in 1985-1989, 1993-1997, and 2003-2006. The collapses had effects both downwards and upwards in the food web. The release in predation pressure from the capelin stock led to increased amounts of zooplankton during the collapse periods. When capelin biomass was drastically reduced, its predators were affected in various ways. Cod experienced increased cannibalism, growth was reduced and maturation delayed. Sea birds experienced increased rates of mortality and total recruitment failures, and breeding colonies were abandoned for several years. Harp seals experienced food shortage, increased mortality because they invaded the coastal areas and were caught in fishing gears, and recruitment failures. There is evidence for differences in how the three capelin collapses affected the predators. The effects were most serious during the 1985-1989 collapse and can hardly be traced during the ongoing collapse. We conclude that these differences likely result from increased availability of alternative food sources during the two last periods of collapse.

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