Marine Protected Areas that restrict fishing provide welfare benefits to fish and other marine animals by reducing direct mortality, habitat destruction and chronic fishing pressure.
Marine Protected Areas benefit fish welfare through multiple mechanisms. The most direct is reducing mortality from fishing gear encounters — fish that escape trawl or longline gear are injured and experience significant stress. In heavily fished areas, the cumulative probability of individual fish encountering gear multiple times is high. MPAs that reduce this pressure allow fish to live without the chronic stress of regular gear encounters. Habitat recovery within effective MPAs restores the complex structures — reefs, seagrass, kelp forests — that fish use for shelter, reducing predation stress. Population recovery within MPAs also allows more natural social and reproductive behaviours. The welfare case for effective MPAs is therefore substantial alongside their conservation rationale.