IUCN Group Says 25% of All Sharks and Rays Threatened with Extinction
A new assessment by fish experts at the International Union for the Conservation of Nature (IUCN) reports one-quarter of the world's sharks and rays to be threatened with extinction.
The study of 1,041 chondrichthyan fishes - sharks, rays, and chimaeras - was carried out by the IUCN Shark Specialist Group (SSG) and published Tuesday in the open-access journal eLife.
Of all the chondrichthyan fishes on the IUCN's Red List of Threatened Species, only 23 percent have populations healthy enough to be considered of "least concern."
The IUCN reports that chondrichthyan fishes are "at a substantially higher risk than most other groups of animals and have the lowest percentage of species considered safe."
"Our analysis shows that sharks and their relatives are facing an alarmingly elevated risk of extinction," said Simon Fraser University's Nick Dulvy, an IUCN SSG co-chair.
"We now know that many species of sharks and rays, not just the charismatic white sharks, face extinction across the ice-free seas of the world," Dulvy said. "There are no real sanctuaries for sharks where they are safe from overfishing." "In greatest peril are the largest species of rays and sharks, especially those living in shallow water that is accessible to fisheries."
The main threat to sharks and rays is overfishing, both targeted and incidental, the report suggests, with the most-threatened species being large-bodied, shallow-water species.
Rays are more threatened than sharks, the researchers said.
"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 Colin Simpfendorfer, a professor of environmental science at James Cook University and IUCN SSG co-chair. "While public, media and government attention to the plight of sharks is growing, the widespread depletion of rays is largely unnoticed. Conservation action for rays is lagging far behind, which only heightens our concern for this species group."
The high value placed on the fins of some sharks and rays - which are used in some Asian cuisine, most notably in shark fin soup - is a major contributor to the threats facing the animals. Other demand is driven by the traditional Chinese medicine market (which sells tonics made of manta and devil ray gills) and the pharmaceutical industry, which uses shark livers in some products.
The Gulf of Thailand and the Mediterranean and Red seas are the regions where the depletion of sharks and rays has been most dramatic.
The ICUN experts report that there is an urgent need to improve management of fisheries and trade in order to avoid extinctions and promote population recovery.
"Sharks, rays and chimaeras tend to grow slowly and produce few young, which leaves them particularly vulnerable to overfishing," said IUCN SSG Deputy Chair Sonja Fordham, president of the Shark Advocates International conservation group. "Significant policy strides have been made over the last two decades but effective conservation requires a dramatic acceleration in pace as well as an expansion of scope to include all shapes and sizes of these exceptional species. Our analysis clearly demonstrates that the need for such action is urgent."