Berlin 2012 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 29: Posters II
DY 29.36: Poster
Thursday, March 29, 2012, 17:00–19:00, Poster A
Effects of introducing a competing salmon species into a model of sockeye salmon population dynamics — •Christoph Schmitt1, Barbara Drossel1, and Christian Guill2 — 1Institut für Festkörperphysik, TU Darmstadt — 2J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August-University Göttingen
The number of spawning sockeye salmon in the Fraser River basin in Canada shows a remarkably strong and regular four-year oscillation. This so-called cyclic dominance phenomenon is reproduced as a stable attractor by a recently introduced three species model for salmon fry, their zooplankton food, and their main predator in the rearing lakes, rainbow trout.
However, this simple model does not take into account that all sockeye rearing lakes also contain kokanee salmon, which belong to the same species as sockeye. Unlike sockeye, which migrate to the ocean at age one, kokanee spend their entire life in the lakes.
We investigate the dynamics of models that include kokanee salmon in addition to the other three species. This increases the predator biomass by providing a stable food source. In the simplest version of the four-species model, cyclic dominance breaks down over a large parameter range, because it reduces the required strong coupling between sockeye and their predators. Because cyclic dominance is observed in nature nevertheless, we also study other versions of the four-species model. In particular, we investigate whether splitting kokanee and/or rainbow trout into different age classes can increase the parameter range over which cyclic dominance is observed.