A third of shark and ray species have been overfished to near extinction, according to an eight-year scientific study.
“Sharks and rays are the canary in the coal mine of overfishing. If I tell you that three-quarters of tropical and subtropical coastal species are threatened, imagine a David Attenborough series with 75% of its predators missing. If sharks are declining, there is a serious problem with fishing, “said the lead author of the paper, Professor Nicholas Dulvy, from Simon Fraser University in Canada.
The health of “entire ocean ecosystems” and food security were in jeopardy, said Dulvy, former co-chair of the shark specialist group at the International Union for Conservation of Nature (IUCN).
The number of species of sharks, rays and chimaeras, known collectively as chondrichthyan fish, facing “a global extinction crisis” has more than doubled in less than a decade, according to the article published today in the magazine. Current Biology journal.
Stingrays are the most threatened, with 41% of the 611 species studied at risk; 36% of the 536 species of sharks are at risk; and 9% of 52 species of chimeras.
Dulvy said: “Our study reveals an increasingly grim reality, with these species now forming one of the most threatened lineages of vertebrates, second only to amphibians in the risks they face.
“The widespread depletion of these fish, particularly sharks and rays, threatens the health of all ocean ecosystems and the food security of many nations around the world,” he said.
The assessment is the second to be carried out since 2014 and comes after a study in January found that shark and ray populations had plummeted by more than 70% in the past 50 years, and previously highly vulnerable species. widespread, like hammerhead sharks, face extinction.
Sharks, rays, and chimaeras are vulnerable to overfishing because they grow slowly and produce few young. Has been Estimate that 100 million sharks are killed by humans each year, overwhelming their slow reproductive capacity. Industrial fishing was a “key threat” to chondrichthyans, either alone or in combination with other fisheries, the authors said.
Most sharks and rays are caught “unintentionally,” but they may be the “unofficial target” in many fisheries, according to the report, and are retained for food and feed. Habitat loss and degradation, the climate crisis and pollution exacerbate overfishing, the authors said.
The species are disproportionately threatened in tropical and subtropical waters, especially in countries such as Indonesia and India, the experts found, due to very high demand from large coastal populations combined with mostly unregulated fisheries, often driven by demand for products. of higher value such as fins. .
Chondrichthyes have survived at least five mass extinctions in their 420 million-year history, according to the report. But, at least three species are now critically endangered and possibly extinct. The Java Stingray has not been recorded since 1868, the Red Sea torpedo ray since 1898 and the lost shark of the South China Sea has not been seen since 1934. Their disappearance would be the first time in the world that marine species have become extinct. due to overfishing.
Colin Simpfendorfer, Adjunct Professor at James Cook University in Queensland, Australia, said: “The tropics are home to an incredible diversity of sharks and rays, but many of these inherently vulnerable species have been intensively fished for more than a century for a long time. range of fisheries that remain poorly managed, despite myriad commitments for improvement.
“As a result, we fear that we will soon confirm that one or more of these species have been driven to extinction by overfishing, a deeply worrisome development for marine fish,” he said. “We will work to make this study a turning point in efforts to prevent further irreversible losses and ensure long-term sustainability.”
The experts, mainly from the IUCN Shark Specialist Group, assessed 1,199 species and classified 391 in the IUCN threatened categories of critically endangered (90 species), endangered (121 species) or vulnerable (180 species).
The most threatened are sawfish, giant guitarfish, devil rays and pelagic eagle rays. More than three-quarters of the species are threatened in the tropics and subtropical coasts, particularly in the northern Indian Ocean, the central western and northwestern Pacific Ocean, from Pakistan to Japan.
The first global assessment in 2014 concluded that a quarter of chondrichthyan species were threatened. One third is now in danger of extinction. However, the authors added that for those species for which data were sparse, the figure rose to almost two-fifths.
Sonja Fordham, co-author and president of Shark Advocates International, an Ocean Foundation project, said: “We all knew sharks were in trouble, but now there is a lot more information, as well as conservation measures, and yet compared to 2014, twice as many species are classified as threatened. That is alarming and shocking, even for the experts. “
While noting that more conservation measures and commitments had been implemented, he called for governments to take urgent action to limit fishing.
“Time is running out for more and more species of sharks and rays,” Fordham said.
The study was completed by the Global Shark Trends Project., an IUCN collaboration shark specialist group, Simon Fraser University, James Cook University and the Georgia Aquarium, funded by the Shark Conservation Fund