Gradually, then suddenly: transient dynamics of declining fisheries in a warming climate

Considerable attention has been devoted to studying the ecological impacts of climate change on fisheries. An understudied component of climate change impacts on fisheries is shifting behavior of fishers in response to warming trends. The extent to which fishers respond to declines in productivity of cold-adapted fish species by either moving to new fishing locations or targeting populations of warm-adapted competitors may alter the trajectories of these declining populations. To understand the potential outcomes of recreational fisheries threatened by climate change, we construct an integrated social-ecological model of an inland recreational fishery along a latitudinal spatial gradient that includes feedbacks between ecological and social dynamics. The model tracks the dynamics of a cold-adapted species and a warm-adapted competitor as well as specialist and generalist fishing communities comprised of individuals that will only fish the cold-adapted species and individuals that fish whichever species is most abundant respectively. We show that specialist fishing exacerbates climate-driven declines, as initial declines in the most equatorward population displace and concentrate harvest pressure poleward. However, generalist fishers willing to switch target species can slow the pace of decline through portfolio diversification. By increasing the harvest rates of a warm-adapted competitor, a generalist fishery can facilitate coexistence and therefore sustainability. Our research sheds light on the critical role that fisher behavior can play in determining the climate resiliency of harvested populations.