Title: Surprising global tradeoffs and synergies between fisheries and conservation
Abstract: Understanding tradeoffs and synergies between stakeholder objectives is a major focus of environmental science. In fisheries, it is conventional wisdom that ending overfishing of target fish stocks offers a synergy between fishery profits, food production, and the ecological health of these target stocks. In contrast, it is conventional wisdom that there is a tradeoff between maintaining fishery profits and conserving marine mammal, turtle, and bird species caught incidentally as fishery bycatch. Using theoretical and empirical evidence, I will argue that situations exactly opposite to these conventional wisdoms are common, especially in coastal waters of the developing world. With bycatch, we find that unsustainable mortality on marine mammal, turtle, and bird species often goes hand-in-hand with overfishing of target fish stocks. Thus, reducing fishing pressure in these fisheries can solve both problems. In contrast, we find that classical single-species models used to manage target fish stocks can sometimes significantly overestimate the food production available in an ecosystem. Indeed, once species interactions are accounted for, we find that there can be a strong tradeoff between target stock health and food production, because the highest-yielding fishing strategies often involve depleting predator fish. Our findings carry important implications for food security and conservation. They also offer generalizable lessons about when resource management for multiple objectives can be made simpler, and when additional complexity is needed.