Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Posters: Statistical Physics in Biological Systems

BP 7.8: Poster

Monday, March 14, 2011, 17:15–20:00, P3

The influence of stochastic fluctuations on the cyclic dominance of pacific salmon — •Christoph Schmitt, Christian Guill, and Barbara Drossel — Institut für Festkörperphysik, TU Darmstadt

The four-year oscillations of the number of spawning sockeye salmon that return from the ocean to their native lake within the Fraser River basin in Canada are a striking example of population oscillations. A recently introduced three-species model for these fish, their predators and their prey, was able to reproduce the four-year oscillation as a stable attractor of the dynamics. This model describes the population dynamics in the lake between spring and fall by coupled differential equations, while the survival of the adult salmon in the ocean and the resulting initial condition in the lake at the beginning of each season are modeled by a discrete map. Since the sockeye populations are subject to various types of fluctuations due to the many factors affecting their growth and survival, we investigate now the behaviour of this model under several types of noise. In particular, we evaluate the frequency of phase shifts in the four-year oscillation, and the extent of synchronization between different sockeye populations.