Overfishing Claims 90 Percent of Predator Fish in Caribbean Reefs

This is an illustration of the relative fish biomass on reefs varying in fishing intensity and natural capacity to support large predatory fishes. (Drawing by Adi Khen)

(CN) – Overfishing has led to a 90 percent decline in predatory fish populations at coral reefs across the Caribbean, disrupting the ocean ecosystem and coastal economy.

In a study published Wednesday in the journal Science Advances, researchers at the University of North Carolina at Chapel Hill recommend prioritizing protection and reintroduction efforts at “supersites” featuring feature nooks and crannies that act as hiding places for prey – and attract predators.

“On land, a supersite would be a national park like Yellowstone, which naturally supports an abundance of varied wildlife and has been protected by the federal government,” John Bruno, co-lead author and marine biologist at UNC-Chapel Hill, said.

Bruno’s team identified the population decline after surveying 39 Caribbean coast reefs across the Bahamas, Florida, Cuba, Mexico and Belize, both inside and outside marine reserves. The data from this survey allowed them to compare fish biomass on pristine sites to fish biomass on a typical reef. They estimated the biomass in each location and found that 90 percent of predatory fish were gone as a result of overfishing.

Despite these grim findings, the team is hopeful that, if protected, a handful of reef locations could substantially aid the recovery of predatory fish populations and help restore depleted species.

A Caribbean reef shark in the Bahamas. (Photo: Neil Hammerschlag)

“Some features have a surprisingly large effect on how many predators a reef can support,” said co-author Ellen Cox, a former UNC-Chapel Hill doctoral student who now works at the National Museum of Natural History in Washington.

Formerly large fish populations on coral reefs are now largely absent due to targeted fishing, and predators are larger and more common within marine reserves than on unprotected reefs. However, some of these marine reserves have also experienced striking declines, owing to the lack of enforcement of fishing regulations.

The team argues that the protection of predatory fish is a win-win, providing both environmental and economic benefits.

“A live shark is worth over a million dollars in tourism revenue over its lifespan because sharks live for decades and thousands of people will travel and dive just to see them up close,” said co-lead author Abel Valdivia. “There is a massive economic incentive to restore and protect sharks and other top predators on coral reefs.”

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