One third of shark and ray species can face extinction

This story originally appeared in The guardian and is part of Air conditioning desk cooperation.

One-third of shark and ray species have been almost extinct, according to an eight-year study.

“Sharks and rays are the canaries in the coal mine during overfishing. If I tell you that three-quarters of tropical and subtropical coastal species are endangered, just imagine a David Attenborough series with 75% of its predators. If the sharks are declining, there is a serious problem with fishing, “said lead author Nicholas Dulvey of the Canadian University of Simon Fraser.

The health of “entire ocean ecosystems” and food security are at stake, said Dulvey, a former co-chair of the International Union for Conservation of Nature (IUCN) shark group.

The number of shark, ray and chimera species known collectively as Hondrichtian fish facing a “global extinction crisis” has doubled in less than a decade, according to a report published September 6 in the journal. Current biology.

The rays are most endangered, as 41% of the 611 studied species are at risk; 36 percent of 536 shark species are at risk; and 9 percent of the 52 species of chimeras.

Dulvey said: “Our study reveals an increasingly bleak reality, with these species now making up one of the most endangered vertebrates, second only to amphibians in the risks they face.”

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

The assessment is the second to be carried out since 2014, and it comes after a study in January found that shark and ray populations have collapsed by more than 70 percent in the last 50 years, having previously been a widespread species, such as Hammerhead sharks are on the verge of extinction.

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

Most sharks and rays are taken “involuntarily”, but they can be the “unofficial target” in many fishing activities, the report said, and are reserved for food and feed. Habitat loss and degradation, the climate crisis and overfishing of pollutant compounds, the authors say.

The species is disproportionately endangered in tropical and subtropical waters, especially in countries such as Indonesia and India, experts said, due to high demand from large coastal populations, combined with mostly unregulated fishing, often driven by demand for higher value products such as fins.

According to the report, the Hondrichts have survived at least five mass disappearances in their 420-year history. But at least three species are now critically endangered and probably extinct. Java stingaree has not been recorded since 1868, the Red Sea beam since 1898, and the lost shark in the South China Sea has not been seen since 1934. Their extinction will be the first time in the world that marine species have become extinct due to overfishing.

Colin Simpfendorfer, an assistant professor at James Cook University in Queensland, Australia, said: “The tropics are home to an incredible variety of sharks and rays, but too many of these inherently vulnerable species have been heavily hunted for more than a century a range of fisheries that remain poorly managed, despite countless commitments to improve.

“As a result, we fear that we will soon confirm that one or more of these species have been brought to extinction by overfishing – a deep concern for marine fish first,” he said. “We will work to make this study a turning point in efforts to prevent more irreversible losses and ensure long-term sustainability.”