Large predatory fishes are disappearing from Caribbean coral reefs, and the region’s food web and fisheries are endangered due to the rise in human population, according to new research by Chris Stallings of The Florida State University Coastal and Marine Laboratory. The new study documents ‘ominous patterns’ in the decline of marine life in the area, and points to the connection between nations with large populations and the endangered state of coral habitats.
“Seeing evidence of this ecological and economic travesty played out across the entire Caribbean is truly sobering.” – Associate Professor John Bruno of the University of North Carolina at Chapel Hill, PLoS One academic editor for Stallings’ paper.
The study, “Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities,” published in the May 6, 2009 issue of the journal PLoS One, documents the decline in greater detail and on a larger geographic scale than any other research to date.
Stallings examined 20 species of predators from 22 Caribbean nations, including sharks, groupers, snappers, jacks, trumpetfish and barracuda, and found that nations with more people have reefs with far fewer large fish due to the increased demand for seafood.
“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
According to Stallings, several factors have contributed to the decline, but his examination of the data suggest that overfishing is the most likely reason for the disappearance of the large predatory fishes once abundant in the Caribbean. He uses the Nassau grouper as an example, saying that they have ‘virtually disappeared’ from Caribbean near shore areas and are considered endangered in their usual range.
“Predicting the consequence of the loss [of large predatory fish] 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. 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.” – Stallings
He points to the example of the invasion of the Pacific lionfish, originally introduced by releases from aquariums. Lionfish populations are exploding in the Caribbean and overeating small fishes in the region.
“Preliminary evidence suggests that lionfish are less invasive where large predatory native fishes are abundant, such as in marine reserves.” – Professor Mark Hixon of Oregon State University
Stallings warned that because half of the world’s population lives near coastlines, and the population is growing, the demand for protein from the ocean will rise with it. Maintaining healthy coral reefs while meeting the demand for seafood will require the implementation of several strategies at once, including establishing marine reserves, increasing family planning efforts, and finding alternative sources of protein foods.
The study is available at PLoS One. For more info on the research, see the Florida State University Coastal and Marine Laboratory site.