The economics of reversing fisheries-induced evolution

Fisheries management typically considers short planning horizons that stand in contrast to long-term sustainability and biodiversity targets, especially when evolutionary timescales play a role. Many fish stocks globally have been exploited above sustainable levels, causing fisheries-induced evolution towards smaller maturation sizes, lower growth rates and lower economic value of individual fish. Here we couple economic decision-making with eco-evolutionary fish population dynamics to explore (1) the impact of alternative planning horizons in profit-maximizing fisheries management on evolution and (2) the trade-off between profit and a set conservation target. We find that evolutionary decline is reversed only under century-long planning horizons. With more typical short-term planning, stock recovery in terms of biomass is achieved, but evolutionary decline continues, albeit at much lower rates. Setting conservation targets for genetic traits only slightly reduces profits, and the trade-off is further alleviated if the fishery can select for genotypes and thereby assist evolutionary reversal. Sustainability goals and biodiversity targets call for restoring not only fish stocks but also their genetic diversity, implying the reversal of fisheries-induced evolution. We show that economic incentives alone may not be sufficient to achieve these sustainability goals.