12 June 2008

Loss of large predatory sharks from the Mediterranean Sea

Several species of sharks in the Med have almost disappeared, their numbers 97% below what they were 200 years ago.

This is the scary figure that emerges from a new research (Loss of large predatory sharks in the Mediterranean), founded in part by the Lenfest Ocean Program, just published on Conservation Biology.

Fishing (both direct and by catch), coastal degradation and lack of management, coupled with the life history of sharks (who grow slowly, mature late and produce few young) caused this massive loss.

Blue, thresher, mako, porbeagle and hammerhead sharks have almost totally vanished in catch records from all sorts of different sources (tuna traps records, coast guard, fishing market, recreational fishing tournaments data) over the years, the authors found.

The consequences on the ecosystem of losing these key players is still poorly understood, as populations of other fish and invertebrates shift in unpredictable ways. But the extent of this collapse "may hold serious implications for the entire marine ecosystem, greatly affecting food webs throughout this region,” said the lead author of the study, Francesco Ferretti, a doctoral student in marine biology at Dalhousie University in Nova Scotia.

Better management of shark fisheries is clearly needed to invert this trend.

Eleonora De Sabata

For more information:
- The press release
- The Lenfest Report "Shark Declines in the Mediterranean sea: a summary of a new scientific analysis"
- Ferretti et al. 2008. Loss of large predatory sharks from the Mediterranean Sea. Conservation Biology.

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