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

Authored by Alistair J Hobday, Christopher J Brown, Philippe E Ziegler, Dirk C Welsford

Date Published: 2008

DOI: 10.3354/meps07601

Sponsors: No sponsors listed

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Model Documentation: Other Narrative Flow charts Mathematical description

Model Code URLs: Model code not found

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.

Tags

Exploitation population Age History Reaction norms Salmon Size-selective mortality Maturation Harvest selection Stocks