Fisheries restoration potential: Optimizing fisheries profits while maintaining food web structure

Abstract There is mounting evidence that fishing impacts can fundamentally alter the structure of whole ecosystems, whereby removal of top trophic levels is expected to generally cascade down the food web, allowing prey at lower trophic levels to flourish. These cascades can lead to decreased diversity but increased productivity in ecosystems, which may lead to increased yields in multi-species fisheries. In a world with a growing human population to feed, increasing consumption of fish protein, and also a growing human footprint on our aquatic ecosystems, this sets up an interesting economic dilemma: do we aim to restore fisheries ecosystems at the expense of foregoing yield? Alternatively, is there a possible way to benefit both restoration and people's livelihoods? Here, we discuss how various market and food web characteristics may allow for equally sustainable and profitable fisheries using a simple food chain model with multi-species fishing pressure. We show that fisheries with higher economic value for top predators relative to intermediate consumers, and with high potential for fisheries-induced trophic cascades, meet criteria for high fishery restoration potential. In these situations, managing fisheries for maximizing profits rather than total productivity can lead to increased maintenance of food web structure and function as well as being economically beneficial. We discuss emerging examples that are consistent with this result.