Protecting 5% More of the Ocean Yields 20% More Fish For Food

Photo: Bruno de Giusti, Wikimedia CC

A new study published this week in the Proceedings of the National Academies of Sciences proves that protecting an additional 5% of the world’s ocean area leads to an increase of 20% more fish for fishermen to catch and thus much more food for people to eat.  It may seem obvious — the more you protect the ocean, the healthier it will be, but often fishermen object to any sort of protection from fishing because the market incentivizes them to catch as many fish as possible in the short run.  But now there is evidence that conservation practices like creating “no fishing” zones with increasing the catch specifically in mind more than pays off.

Why This Matters:  Right now only 2.5% of the ocean is fully protected, but the goal is 30% protected by 2030. As one of the study’s authors, Dr. Enric Sala of National Geographic, told ODP, “There is a myth that we cannot protect more of the ocean because we need to catch more fish. But most fish stocks are depleted or collapsed because of too much fishing. Our research shows that more protection would actually help replenish these depleted fish stocks. Yet, we still need fisheries agencies around the world to do their job well and manage fishing more responsibly.”  And if they do, we will have more food for people not less.

Spillover Effect

Ariella Simke of Forbes explains that scientists (and indigenous peoples) already knew that marine protected areas have a “spillover” effect — that fish in MPAs are able to grow bigger and produce a greater number of stronger offspring that eventually swim into unprotected areas and are caught by fishers.  This study went one step farther and scaled up protection to determine how much more fish we could have if we implemented protected areas strategically to try to yield more fish. The scientists examined areas of 55 kilometers by 55 kilometers and calculated the biomass of species in each area.  Then by taking into account fish biology and movements, they calculated how much fish catch would be possible if the area was fully protected, and then subtracted out the amount of fish currently being harvested there and came up with an estimate of how much fish catch would increase with greater protections.

What they found was that “strategically expanding the existing global MPA network to protect an additional 5% of the ocean could increase future catch by at least 20% via spillover, generating 9 to 12 million metric tons more food annually than in a business-as-usual world with no additional protection.”  In the business world, that would be a very good return on investment.  And that is a great deal more food as well — a very important consideration given the population growth and the increasing need for healthy sources of protein like fish.  When you think of it that way, it is hard to see the arguments against this approach.  Increased marine protection leads to more fish to feed people — it’s a win, win.


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