Humans linked to decline of reef fish

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, new research shows. A sweeping study by a Florida researcher, published by the journal PLoS ONE, comprehensively documents the patterns, Science reported.


Scientists working in the Caribbean have observed the declines of large predators for decades. However, Chris Stallings of the Florida State University Coastal and Marine Laboratory examined 20 species of predator fish from 22 countries’ waters, producing findings in far more detail and on a much greater geographic scale.


“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,” said Stallings. “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.”


Stallings said that although several factors — including loss of coral reef habitats — contributed to the general patterns, careful examination of the data suggests that overfishing was the most likely reason for the disappearance of larger fishes across the Caribbean region. He noted: “Predicting the consequence of their loss is difficult because of the complexity of predator-prey interactions. … Shifts in abundance to smaller predators could therefore have surprising and unanticipated effects.”


Given that about half the world’s populations live near coastlines and that the world population is growing, Stallings said, demands for ocean-derived protein will continue to increase. Meeting such demands while retaining healthy coral reefs may require multiple strategies, he added.


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