Fishing Leads to Significant Shark Population Declines
MIAMI, March 1, 2013 /PRNewswire-USNewswire/ -- The world's shark population is experiencing significant decline with perhaps 100 million or more sharks being lost every year, according to a study published this week in Marine Policy.
While sharks are one of the oldest vertebrate groups on the planet, the population decline is causing global concern.
In the recently published paper, "Global Catches, Exploitation Rates and Rebuilding Options for Sharks," researchers from Dalhousie University and University of Windsor in Canada, as well as Stony Brook University in New York, Florida International University (FIU) in Miami and the University of Miami calculate total shark mortality and outline possible solutions to protect the world's shark population.
"This is a big concern because the loss of sharks can affect the wider ecosystem," said Mike Heithaus, executive director of FIU's School of Environment, Arts and Society and co-author of the paper. "In working with tiger sharks, we've seen that if we don't have enough of these predators around, it causes cascading changes in the ecosystem, that trickle all the way down to marine plants."
Such changes can harm other species, and may negatively affect commercial fisheries, according to Heithaus. Based on data collected, shark deaths were estimated at 100 million in 2000 and 97 million in 2010. The total possible range of mortality is between 63 and 273 million annually.
The biggest culprit in the significant decline is a combination of a global boom in shark fishing — usually for their valuable fins — and the slow growth and reproductive rates of sharks. Because adequate data of shark catches is lacking for most of the world, the wide range of possible mortality is based on available data of shark deaths and calculated projections for unreported, discarded and illegal catches.
"Our analysis shows that about one in 15 sharks gets killed by fisheries every year," said Boris Worm, lead author and professor of biology at Dalhousie. "With an increasing demand for their fins, sharks are more vulnerable today than ever before."
While some sharks receive protection through national and international agreements, the researchers suggest legislation should be expanded to more species. Catch limits, trade regulations and other protective measures for the most vulnerable species can also help, while imposing a tax on shark fins could curb demand, according to the study.
SOURCE Florida International University