Are there plenty of fish in the sea? How life history traits affect the eco-evolutionary consequences of population oscillations

Abstract

Understanding fish population oscillations is important for both fundamental population biology and for fisheries science. Much research has focused on the causes of population oscillations, but the eco-evolutionary consequences of population oscillations are unclear. Here, we used an empirically parametrised individual-based simulation model to explore the consequences of oscillations with different amplitudes and wavelengths. We show that oscillations with a wavelength shorter than the maximum lifespan of the fish produce marked differences in the evolutionary trajectories of asymptotic length. Wavelengths longer than the maximum lifespan of the fish, in turn, mainly manifest as ecological effects seen as the population biomass oscillation. The evolutionary and ecological differences increase with increasing amplitude, however, the two-year wavelength causes opposing results from all the other scenarios. This is likely facilitated by the relatively stable number of fish in the population as a poor year is always counteracted by the previous good year and vice versa. Our results highlight the evolutionary signatures and following ecological consequences that natural population oscillations can cause.