Sharks are ‘functionally extinct’ from one-in-five coral reefs, according to comprehensive three-year survey
- A global survey paints a gloomy portrait of reef sharks populations
- In a three-year survey of 371 reefs around the world scientists found that almost 20 percent didn’t harbor a single reef shark
- Overfishing and human populations density are the biggest factors
- Shark sanctuaries were effective in protecting populations
An extensive study on shark populations has some disconcerting news about reef sharks’ longevity.
In a global study of coral reefs launched by two marine biologists from Florida International University called Global FinPrint, 120 scientists from around the world determined that sharks are missing from 19 percent of the world’s coral reefs.
The study, published in Nature, used 18,000 hours of underwater camera footage over the course of three years to survey 371 tropical reefs across the world’s oceans.
Species the like grey reef shark (pictured) have declined among the world’s coral reefs, with 19 percent of the surveyed areas showing no signs of any sharks at all (stock)
According to the scientists, at 69 of the reefs not a single shark was witnessed during their observation period and were almost completely absent from reefs in several nations studied.
As noted by Science, sharks are particularly vulnerable to overfishing compared to some other marine animals since they grow slowly and don’t produce many offspring.
Additionally, demand for shark fin as a source of protein has grown due to a large middle class in Asia.
Concurrently, some cultures are eating more shark meat as opposed to other types of fish as populations of those historically popular species have also declined in number.
Researchers note that not every reef surveyed was devoid of shark populations, including areas like French Polynesia which, according to a statement to Science from Aaron MacNeil, a reef ecologist at Dalhousie University who led the design of the sampling is a ‘gorgeous utopia, especially if you’re into reef sharks.’
The Bahamas was first among all areas surveyed in terms of numbers of reef sharks while Guam ranked last.
The disparity between surveyed area is due mostly to human population density and nearby fishing practices.
MacNeil used data from the survey to create a computer model the factored in those practices and cross-referenced them against shark populations and found that declared areas protecting sharks tended to have the highest populations.
‘…opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks,’ write the researchers in their paper.