Community reorganization in the Gulf of Alaska following ocean climate regime shift

Abstract

A shift in ocean climate during the late 1970s triggered a reorganization of community structure in the Gulf of Alaska ecosystem, as evidenced in changing catch composi- tion on long-term (1953-1997) small-mesh trawl surveys. Forage species such as pandalid shrimp and capelin declined because of recruitment failure and predation, and populations have not yet recovered. Total trawl catch biomass declined > 50% and remained low through the 1980s. In contrast, recruitment of high trophic-level groundfish improved during the 1980s, yielding a > 250% increase in catch biomass during the 1990s. This trophic reorganization apparently had negative effects on piscivorus sea birds and marine mammals.