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One-quarter of shark and ray species are in trouble

The first global analysis of the threats to sharks and their kin suggests that about one-quarter of all the world’s species are at risk.

Nicholas Dulvy, a marine ecologist at Simon Fraser University in Burnaby, Canada, and his colleagues analysed 1,041 species of cartilaginous fishes, or chondrichthyans — the group that encompasses sharks, rays and ‘ghost sharks’, also known as chimaeras (see ‘Why sharks have no bones‘). Of these, 25 species are critically endangered, 43 are endangered and 113 are vulnerable according to the ‘red list’ criteria of the International Union for the Conservation of Nature (IUCN); an additional 132 species are classed as ‘near threatened’, while there was insufficient data to make a decision in 487 cases, Dulvey and his collaborators report in the journal eLife.

“In greatest peril are the largest species of rays and sharks, especially those living in shallow water that is accessible to fisheries,” said Dulvy in a statement. Dulvy also co-chairs the IUCN’s Shark Specialist Group.

Extinction risk among these animals is “substantially higher” than for most other vertebrates, write Dulvy and his colleagues, with deliberate and accidental targeting by fishing the main culprit.

“Chondrichthyans have slipped through the jurisdictional cracks of traditional national and international management authorities,” warn the authors in their paper. “Rather than accept that many chondrichthyans will inevitably be driven to economic, ecological, or biological extinction, we warn that dramatic changes in the enforcement and implementation of the conservation and management of threatened chondrichthyans are urgently needed to ensure a healthy future for these iconic fishes and the ecosystems they support.”

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