Fish, whether wild caught or farmed, now make up nearly a fifth of the animal protein that human beings eat….In this context, running the world’s fisheries efficiently might seem a sensible idea. In practice, that rarely happens. Even well-governed coastal countries often pander to their fishing lobbies by setting quotas which give little respite to battered piscine populations. Those with weak or corrupt governments may not even bother with this. Deals abound that permit outsiders legal but often badly monitored access to such countries’ waters. And many rogue vessels simply enter other people’s fishing grounds and steal their contents.
There may be a way to improve the supply side: increase the area where fishing is forbidden altogether. This paradoxical approach, which involves the creation of so-called marine protected areas (MPAs), has already been demonstrated on several occasions to work locally. A new study “A global network of marine protected areas for food “in the Proceedings of the National Academy of Sciences…explores the idea of extending MPAs elsewhere. If the right extensions are picked designating a mere 5% more of the world’s oceans as MPAs—which would triple the area protected—could increase the future global catch of the 811 species they looked at by more than 20%. That corresponds to an extra 10m tonnes of food a year.
The idea that restricting fishing would permit more fish to be caught may seem counterintuitive, but the logic is simple. Fish in MPAs can grow larger than those at constant risk of being pulled from the ocean. Larger fish produce more eggs. More eggs mean more fry. Many of these youngsters then grow up and move out of the safe zone, thus becoming available to catch in adjoining areas where fishing is permitted…
MPAs are especially beneficial for the worst-managed areas, most of which are tropical—and in particular for overfished species…They also have the virtue of simplicity. The setting of quotas is open to pressure to overestimate of how many fish can safely be caught…This is difficult enough for countries with well-developed fisheries-research establishments. For those without such it is little more than guesswork…Setting the rules for an MPA is, by contrast, easy. You stick up a metaphorical sign that says, “No fishing”. Knowing who is breaking the rules is easy, too. If your gear is in the water, you are fishing illegally.
Excerpt from Fishing: Stopping some fishing would increase overall catches. Economist, Oct. 31, 2020