A three-species model explaining cyclic dominance of pacific salmon

Christian Guill (1) , Barbara Drossel (1) , Wolfram Just (2) , Eddy Carmack (3)

1 Institut für Festkörperphysik
2 QMUL - Queen Mary University of London
3 Institute of Ocean Sciences

The four-year oscillations of the number of spawning sockeye salmon () that return to their native stream within the Fraser River basin in Canada are a striking example of population oscillations. The period of the oscillation corresponds to the dominant generation time of these fish. Various - not fully convincing - explanations for these oscillations have been proposed, including stochastic influences, depensatory fishing, or genetic effects. Here, we show that the oscillations can be explained as an attractor of the population dynamics, resulting from a strong resonance near a Neimark Sacker bifurcation. This explains not only the long-term persistence of these oscillations, but also reproduces correctly the empirical sequence of salmon abundance within one period of the oscillations. Furthermore, it explains the observation that these oscillations occur only in sockeye stocks originating from large oligotrophic lakes, and that they are usually not observed in salmon species that have a longer generation time.

Mots clés: Cyclic dominance; Population oscillations; Single-generation cycles; Neimark Sacker bifurcation; Strong resonance

Domaines: Sciences du Vivant [q-bio]

Christian Guill, Barbara Drossel, Wolfram Just, Eddy Carmack. A three-species model explaining cyclic dominance of pacific salmon. Journal of Theoretical Biology, 2011, 276 (1), pp.16. ⟨10.1016/j.jtbi.2011.01.036⟩. ⟨hal-00682411⟩