Humans have been overfishing Caribbean reefs for decades or even centuries. And you don’t have to be a scientists to have noticed. Countless reefs once dominated by vertebrate predators are now nearly devoid of large fish.
Sharks and large grouper and snapper are a rarity on most Caribbean reefs. The reason isn’t a mystery; we simply removed them for sport, profit or sustenance. But the spatio-temporal patterns of predatory fish loss-where and when it happened-and how it was related to factors like proximity to people is largely unknown.
A new study just published in PLoS One by Dr. Chris Stallings sheds some light on the issue by documenting the dissapearence and reduction in size of predatory fish across the Caribbean. The study is based on a publicly accessible, fisheries-independent database of 38,116 reef surveys conducted between 1994 and 2008. Chris examined 20 species of top-level predators, including sharks, groupers, snappers, jacks, trumpetfish and barracuda, from 22 Caribbean nations. He 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.
Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species.
The study nicely complements another recent study on Caribbean reef fish decline (Paddack et al 2009) covered here in Climate Shifts. One of the many advances of both papers is that they describe the Caribbean-wide loss of reef fish in greater detail than previous local studies. Seeing evidence of this ecological and economic travesty played out across the entire Caribbean is truly sobering.
“Although several factors–including loss of coral reef habitats–contributed to the general patterns, careful examination of the data suggests overfishing is the most likely reason we are seeing the disappearance of large predatory fishes across the region,” says Stallings.
Species like Nassau grouper, which was once abundant throughout the Caribbean, have completely disappeared from many Caribbean nearshore areas and are endangered throughout their range.
“This study also demonstrates the power of volunteer and community research efforts by non-scientists,” – Dr. Chris Stallings
Chris used data from the Reef Environmental Education Foundation’s (REEF) online database, which contains fish sightings documented by trained volunteer SCUBA divers, including here over 38,000 surveys spanning a fifteen year period.
“Chris was completely undaunted by the lack of fisheries data and essentially adopted the ‘Audubon Christmas Bird Count’ approach in a marine system to find strong evidence for a native fisheries effect,” says Dr. Felicia Coleman, director of the Florida State University Coastal and Marine Laboratory and Stallings’ postdoctoral advisor.
Stallings CD, 2009 Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities. PLoS ONE 4(5): e5333. doi:10.1371/journal.pone.0005333
For additional information, please visit http://www.marinelab.fsu.edu/news/predators
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