Two thirds of reef sharks and rays risk extinction

Nearly two thirds of the sharks and rays that live among the world's corals are threatened with extinction, according to new research published on Jan. 17, with a warning this could further imperil precious reefs.

Coral reefs, which harbor at least a quarter of all marine animals and plants, are gravely menaced by an array of human threats, including overfishing, pollution and climate change.

Shark and ray species - from apex predators to filter feeders - play an important role in these delicate ecosystems that "cannot be filled by other species," said Samantha Sherman, of Simon Fraser University in Canada and the wildlife group TRAFFIC International.

But they are under grave threat globally, according to the study in the journal Nature Communications, which assessed extinction vulnerability data from the International Union for Conservation of Nature (IUCN) to look at 134 species of sharks and rays linked to reefs.

The authors found 59 percent of coral reef shark and ray species are threatened with extinction, an extinction risk almost double that of sharks and rays in general.  

Among these, five shark species are listed as critically endangered, as well as nine ray species, all so-called "rhino rays" that look more like sharks than stingrays.

"It was a bit surprising just how high the threat level is for these species," Sherman told AFP.

"Many species that we thought of as common are declining at alarming rates and becoming more difficult to find in some places." 

Sherman said the biggest threat to these species by far is overfishing. Sharks are under most threat in the Western Atlantic and parts of the Indian Ocean, whereas the Indian Ocean and Southeast Asia are the highest risks for rays. 

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