Surprising tradeoffs and synergies between global fishery catch and conservation
According to conventional wisdom in fishery science: rebuilding overfished target stocks both increases fishery catches and improves the health of these target stocks, but there are often tradeoffs between maximizing catches or profits from target stocks and preventing severe depletions of megafauna threatened by fishery bycatch, such as marine turtles, mammals and birds. Using theory and diverse empirical examples, I will argue that—especially in the developing world—the exact opposite may be the case more often than we expect. Many developing countries have managed to sustain high catches through long histories of intense and lightly managed fishing, and there is new evidence to suggest that predator release may have been a key mechanism allowing these high catches to be sustained. This means that single-species management aimed at rebuilding overfished target stocks might actually decrease ecosystem-wide yield in many cases. In contrast, we found evidence suggesting that unsustainable bycatch mortality on megafauna may in many cases be a side effect of overfishing the target stocks, rather than a sign of a tradeoff, especially in parts of the world where overfishing is still severe and widespread. Specifically, we estimate that maximizing profits from target stocks globally would collaterally halt or reverse the declines of roughly half of marine turtles, mammals and birds threatened by bycatch globally.
Host: Robert Arlinghaus