Protecting algae-eating fish may not be enough to save endangered coral reefs, a new study shows.

Some researchers, resource managers, and conservationists have advocated restoring populations of algae-eating reef fish, such as parrotfish in order to boost resilience resilience of the world’s coral reefs.

According to this idea, which is known as fish-mediated resilience, protecting the fish that keep algae in check leads to healthier corals and can promote the recovery of distressed reefs.

But the new study that analyzed long-term data from 57 coral reefs around the French Polynesian island of Mo’orea challenges this canon of coral reef ecology, providing compelling new evidence that fish don’t regulate coral over time.

“This paper very well might radically change how we think about the conservation of coral reefs,” says Jacob Allgeier, assistant professor in the ecology and evolutionary biology department at the University of Michigan and co-senior author of the study in the journal Nature Ecology & Evolution.

“People have been saying for years that we can protect coral through fisheries management, and our work on Mo’orea reefs shows that this is unlikely to work—there are too many other things going on. There is functionally no measurable effect of fishes on coral cover over time.”

Support for the idea of fish-mediated coral reef resilience has led to calls for moratoriums on fishing for algae-eating reef fish to prevent algae overgrowth and reef degradation. Such well-intentioned but misguided management strategies could have huge implications for the millions of people who depend on coral-reef fisheries for food and income, according to the authors of the new study.

Instead, it makes more sense to support strategies that promote the conservation of diverse habitats and coral reef types at various stages of degradation, the researchers say.

“We do need to manage fisheries in these ecosystems, but instead of things like wholesale restrictions on parrotfish, we should consider management efforts that promote sustainable harvest throughout the food web to disperse the impacts of fishing,” Allgeier says.

Coral reefs are among the most biodiverse and productive ecosystems on the planet, but they are also among the most imperiled and rapidly changing.

Read the full article about protecting coral reefs by Jim Erickson at Futurity.