One quarter of the world's cartilaginous fish such as sharks and rays are in danger of disappearing within the next few decades.
The survey is the first to stretch their observations into "coastal seas and oceans." They found 249 (one-quarter) out of 1,041 shark, chimaera and ray species are considered threatened under the IUCN red list, a Simon Fraser University news release reported.
"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," Nick Dulvy, a Simon Fraser University (SFU) Canada Research Chair in Marine Biodiversity and Conservation, said in the news release. "There are no real sanctuaries for sharks where they are safe from overfishing."
A study involving 300 experts and taking place over 20 years took "distribution, catch, abundance, population trends, habitat use, life histories, threats and conservation measures" into account when looking at the conservation status of the species'.
One-hundred-and-seven species of rays and skates and 74 shark species were defined as "threatened." Only 23 percent of all the species studied were considered to be of "Least Concern."
The team found the regions where these species were most threatened were the Indo-Pacific, the Red Sea, and the Mediterranean.
"In the most peril are the largest species of rays and sharks, especially those living in relatively shallow water that is accessible to fisheries. The combined effects of overexploitation-especially for the lucrative shark fin soup market-and habit degradation are most severe for the 90 species found in freshwater," Dulvy said.
"A whole bunch of wildly charismatic species is at risk. Rays, including the majestic manta and devil rays, are generally worse off than sharks. Unless binding commitments to protect these fish are made now, there is a real risk that our grandchildren won't see sharks and rays in the wild," he said.
Losing some of the aquatic food chain's top predators could cause problems throughout the entire ecosystem. The loss of these species would also be like losing "a chapter of our evolutionary history," according to Dulvy.
"They are the only living representatives of the first lineage to have jaws, brains, placentas and the modern immune system of vertebrates," he said.