One-third of shark and ray species are threatened with extinction, study finds

One-third of shark and ray species are threatened with extinction, study finds

A third of shark and ray species have been overexploited to extinction, according to an eight-year scientific study.

“Sharks and rays are the canary in the overfishing coal mine. If I tell you that three quarters of tropical and subtropical coastal species are threatened, imagine a David Attenborough series where 75% of its predators are extinct. If the sharks are in decline, there is a serious problem with the fishery, ”said lead author Professor Nicholas Dulvy of Simon Fraser University in Canada.

The health of “all ocean ecosystems” and food security were at risk, said Dulvy, former co-chair of the shark specialist group of the International Union for the 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 today in the journal Current Biology.

Rays are the most threatened, with 41% of the 611 species studied at risk; 36% of the 536 shark species are at risk; and 9% of the 52 species of chimeras.

Dulvy said: “Our study reveals an increasingly grim reality, these species are now one of the most endangered lineages of vertebrates, just behind amphibians in the risks they face.

“The widespread depletion of these fish, especially sharks and rays, threatens the health of entire ocean ecosystems and the food security of many countries around the world,” he said.

Manta rays on the beach in Gaza City. Rays are the most threatened chondrichthyan fish, with 41% of species at risk. Photographie : Mohammed Abed/AFP/Getty Images

The assessment is the second to be completed since 2014 and comes after a study in January found that shark and ray populations have collapsed by more than 70% in the past 50 years, previously widespread species. such as hammerhead sharks being threatened with extinction.

Sharks, rays and chimaeras are vulnerable to overfishing because they grow slowly and produce few young. It is estimated that 100 million sharks are killed by humans each year, overwhelming their slow reproductive capacity. Industrial fishing was a “key threat” to chondrichthyans, alone or in combination with other fisheries, the authors said.

Most sharks and rays are caught “unintentionally”, but can be the “unofficial target” in many fisheries, according to the report, and are kept for food and feed. Habitat loss and degradation, the climate crisis and pollution are exacerbating overfishing, the authors say.

The species are disproportionately threatened in tropical and subtropical waters, especially off countries such as Indonesia and India, experts have found, due to very high demand from large coastal populations combined with fisheries. mostly unregulated, often driven by demand for higher value products such as fins. .

According to the report, chondrichthyans have survived at least five mass extinctions during their 420m history. But, at least three species are now critically endangered and possibly extinct. The Java stingaree has not been recorded since 1868, the Red Sea torpedo ray since 1898, and the South China Sea lost shark has not been seen since 1934. Their disappearance is said to be the first time in the world. that marine species are becoming extinct due to overfishing.

A stingray among the catch of a trawler off The Gambia, West Africa. Sharks and rays could be unofficial targets of many fisheries, according to the report. Photography: Christiano Menci / Sea Shepherd

Colin Simpfendorfer, assistant professor at James Cook University in Queensland, Australia, said: remain mismanaged, despite countless improvement commitments.

“As a result, we are concerned that we will soon confirm that one or more of these species have become extinct due to overfishing – a deeply troubling first for marine fish,” he said. “We will work to make this study a turning point in efforts to prevent irreversible loss and ensure long-term sustainability. “

Experts, mainly from the IUCN Shark Specialist Group, assessed 1,199 species and classified 391 of them as threatened by the IUCN: critically endangered (90 species), endangered (121 species) or vulnerable (180 species).

The most threatened are sawfish, giant sea bass, devil rays and pelagic eagle rays. More than three-quarters of the species are threatened on the tropical and subtropical coasts – especially in the northern Indian Ocean, the central-west and the northwest of the Pacific Ocean -om Pakistan to Japan.

The first global assessment in 2014 concluded that a quarter of chondrichthyan species were threatened. A third is now threatened with extinction. However, the authors added that for species for which data was scarce, the figure reached nearly two-fifths.

Sonja Fordham, co-author and chair of Shark Advocates International, an Ocean Foundation project, said: Twice as many species are classified as threatened. It is alarming and shocking, even to the experts.

While noting that more conservation measures and commitments had been put in place, she called on governments to take urgent action to limit fishing.

“Time is running out for more and more species of sharks and rays,” said Fordham.

The study was carried out by the Global Shark Trends Project, a collaboration of IUCN shark specialist group, Simon Fraser University, James Cook University and the Georgia Aquarium, funded by the Shark Conservation Fund


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