Caribbean’s predatory fishes decline as human populations rise

May 6th, 2009 - 5:03 pm ICT by ANI  

Washington, May 6 (ANI): In a new study, scientists have found that sharks, barracuda and other large predatory fishes disappear on Caribbean coral reefs as human populations rise, endangering the region’s marine food web and ultimately its reefs and fisheries.

The study was done by researcher Chris Stallings of The Florida State University Coastal and Marine Laboratory.

While other scientists working in the Caribbean have observed the declines of large predators for decades, the comprehensive work by Stallings documents the ominous patterns in far more detail at a much greater geographic scale than any other research to date.

“Seeing evidence of this ecological and economic travesty played out across the entire Caribbean is truly sobering,” said Associate Professor John Bruno of the University of North Carolina at Chapel Hill.

“I examined 20 species of predators, including sharks, groupers, snappers, jacks, trumpetfish and barracuda, from 22 Caribbean nations,” said Stallings. “I found that nations with more people have reefs with far fewer large fish because as the number of people increases, so does demand for seafood,” he added.

Fishermen typically go after the biggest fish first, but shift to smaller species once the bigger ones become depleted.

“In some areas with large human populations, my study revealed that only a few small predatory fish remain,” said Stallings.

Stallings said that although several factors, including loss of coral reef habitats, contributed to the general patterns, careful examination of the data suggests overfishing as the most likely reason for the disappearance of large predatory fishes across the region.

“Large predatory fish such as groupers and sharks are vitally important in marine food webs,” Stallings said.

“However, predicting the consequence of their loss is difficult because of the complexity of predator-prey interactions. You can’t replace a 10-foot shark with a one-foot grouper and expect there to be no effect on reef communities,” he added.

“Shifts in abundance to smaller predators could therefore have surprising and unanticipated effects. One such effect may be the ability of non-native species to invade Caribbean reefs,” he further added.

Given that about half the world’s populations live near coastlines and that the world population is growing, demands for ocean-derived protein will continue to increase, Stallings warned.

He said meeting such demands while retaining healthy coral reefs may require multiple strategies, including implementation of marine reserves, finding alternative sources of protein, and increased efforts to implement family-planning strategies in densely populated areas. (ANI)

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