Darwinian fisheries science needs to consider realistic fishing pressures over evolutionary time scales

Abstract

The apparently intense selective differentials imposed by many fisheries may drive the rapid evolution of growth rates. In a widely-cited laboratory experiment, Conover & Munch (2002; Science 297:94–96) found considerable evolutionary change in the size of harvested fish over 4 generations. Their empirical model has since been used to estimate the impact of fishery-driven evolution on fishery sustainability. Using a mathematical, individual-based model (IBM) that simulates that experiment, we showed that the selection imposed in the Conover & Munch (2002) model is unrealistically strong when compared to harvest rates in wild fisheries. We inferred the evolutionary change that could be expected over the timescale used by Conover & Munch (2002), had they simulated more realistic harvest regimes, and found that the magnitude in their original experiment was 2.5 to 5 times greater. However, over evolutionary timescales of 30 generations and with realistic fishing pressure, the results of Conover & Munch (2002) are comparable to wild fisheries. This simulation result provides support for the use of empirical models to predict the impacts of fishery-driven evolution on yields and sustainability. Future models should consider the timing of fishing events, the trade-off between size, maturation and growth, and density-dependent effects for a comprehensive analysis of the consequences of fishery-driven evolution.