Shark Fisheries Globally Unsustainable: 100 Million Sharks Die Every Year

Mar. 1, 2013 — The world's shark populations are experiencing significant declines with perhaps 100 million -- or more -- sharks being lost every year, according to a study published this week in Marine Policy.

"Sharks have persisted for at least 400 million years and are one of the oldest vertebrate groups on the planet. However, these predators are experiencing population declines significant enough to cause global concern," explains lead author Boris Worm, professor of biology at Dalhousie.

In the recently published paper, "Global Catches, Exploitation Rates and Rebuilding Options for Sharks," Worm and three other researchers from Dalhousie University teamed up with scientists from the 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, to calculate total shark mortality and outline possible solutions to protect the world's shark populations.

"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, Heithaus explains.

Continued: http://www.sciencedaily.com/releases/2013/03/130301153245.htm