Ottar N Bjørnstad, Jean-Marc Fromentin, Nils Chr Stenseth, Jakob Gjøsæter

1999/4/27

Proceedings of the National Academy of Sciences

96

9

5066-5071

National Acad Sciences

Abstract Year-to-year fluctuations in fish stocks are usually attributed to variability in
recruitment, competition, predation, and changes in catchability. Trends in abundance, in
contrast, are usually ascribed to human exploitation and large-scale environmental
changes. In this study, we demonstrate, through statistical modeling of survey data (1921–
1994) of cod from the Norwegian Skagerrak coast, that both short-and long-term variability
may arise from the same set of age-structured interactions. Asymmetric competition and ...