At least one in every four existing species of sharks and rays may not survive into the future, finds the first global analysis of the conservation status of 1,041 shark, ray and related species.
This study, conducted by the IUCN Shark Specialist Group, marks the 50th anniversary year of The IUCN Red List.
“Our analysis shows that sharks and their relatives are facing an alarmingly elevated risk of extinction,” said Dr. Nick Dulvy, IUCN Shark Specialist Group Co-Chair and Canada Research Chair at Simon Fraser University in British Columbia.
“In greatest peril are the largest species of rays and sharks, especially those living in shallow water that is accessible to fisheries,” he said.
Overfishing is the main threat to the species, finds the study, the product of 302 experts from 64 countries.
The Indo-Pacific, particularly the Gulf of Thailand and the Mediterranean Sea are the two spots where the depletion of sharks and rays is most dramatic. Also, the Red Sea is inhabited by many threatened sharks and rays, according to the experts.
The 1,041 cartilagenous fish species studied include sharks and rays as well as chimaeras, cartilaginous fish that live deeper than 650 feet below the surface.
The skeletons of these cartilagenous fish are made of cartilage rather than bone, making them desirable for food or pharmaceuticals.
“The global market for shark fins used in shark fin soup is a major factor in the depletion of not only sharks but also some rays with valuable fins, such as guitarfish,” the scientists say.
Sharks, rays and chimaeras are also sought for their meat, pharmaceuticals are made from deep sea shark livers, while manta and devil rays are used in a Chinese tonic.
The sharks, rays and chimaeras are at a “substantially higher risk than most other groups of animals and have the lowest percentage of species considered safe – with only 23 percent categorized as Least Concern,” the authors state.
The study finds that reported catches of sharks, rays and chimaeras peaked in 2003, but the authors warn that actual catches “are likely to be grossly under-reported.”
Reported catches have been dominated by rays for the last 40 years, the experts calculated.
“Surprisingly, we have found that the rays, including sawfish, guitarfish, stingrays, and wedgefish, are generally worse off than the sharks, with five out of the seven most threatened families made up of rays,” said Dr. Colin Simpfendorfer, IUCN Shark Specialist Group co-chair and professor of environmental science at James Cook University in Queensland, Australia.
Unintentionally caught sharks and rays account for much of those killed, yet developing markets and depleting fishery targets have made this “bycatch” increasingly welcome.
“While public, media and government attention to the plight of sharks is growing, the widespread depletion of rays is largely unnoticed,” said Simpfendorfer. “Conservation action for rays is lagging far behind, which only heightens our concern for this species group.”