Study says 90 percent of all predatory fish species have been lost from Caribbean coral reefs
Not all Caribbean reefs are created equal, say researchers with the University of North Carolina at Chapel Hill, who recently identified reef areas they are calling “supersites”that could help restore populations of predatory fish needed maintain an ecological balance.
That’s the good news. The bad news is their study also shows that up to 90 percent of predatory fish are gone from Caribbean coral reefs. The research suggests that these supersites should be prioritized for protection and could serve as regional models showcasing the value of biodiversity for tourism and other uses.
The supersites are highly textured reefs that offer habitat for a wide variety of species. They also have abundant sources food and are often found close to coastal mangrove forests, which are nursery areas for young fish.
“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,” said John Bruno, a marine biologist at UNC College of Arts & Sciences.
The study covered 39 reefs across the Bahamas, Cuba, Florida, Mexico and Belize, both inside and outside marine reserves. It was aimed at determining how many fish had been lost by comparing 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 due to overfishing. The findings were published in the March 1 issue of Science Advances.
“Some features have a surprisingly large effect on how many predators a reef can support,” said Courtney Ellen Cox, a coauthor and former UNC-Chapel Hill doctoral student now at the National Museum of Natural History in Washington, D.C. For example, researchers believe that the Columbia Reef within the fisheries closures of Cozumel, Mexico, could support an average 10 times the current level of predatory fish if protected.
Not long ago, large fishes were plentiful on coral reefs, but are now largely absent due to targeted fishing. Today, predators are larger and more abundant within the marine reserves than on unprotected, overfished reefs. But even some of the marine reserves have seen striking declines, largely due to lack of enforcement of fishing regulations.
The bottom line is protection of predatory fish is a win-win from both an environmental and an economical perspective, said Bruno.
“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 Valdivia, now at the Center for Biological Diversity in Oakland, Calif. “There is a massive economic incentive to restore and protect sharks and other top predators on coral reefs.”