Shark and ray populations plummeted by 70% and are near ‘point of no return’, study warns

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“Knowing that this is a global number, the results are startling,” said Nick Dulvy, a biologist at Simon Fraser University and co-author of the study. “If we don’t do anything, it will be too late. It is much worse than the other animal populations we have examined.”

Of the 31 species of sharks and ocean rays, 24 are now threatened with extinction, several of which are classified as critically endangered – the most threatened category.

“It’s an incredible rate of decline, steeper than most elephant and rhino declines, and these animals are iconic in driving conservation efforts on earth,” Dulvey said.

In the study, the researchers used two major indicators of biodiversity – the Red List Index, a list measuring the risk of extinction, and the Living Planet Index, a dataset measuring changes in the abundance of population – to map the rate of change in populations of species over the decades.

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Their results revealed “an alarming and continuing global decline in oceanic shark populations in the world’s largest ecosystem over the past half-century, resulting in an unprecedented increase in the risk of extinction of these species,” the study said. .

Factors such as human disturbance and climate change are putting pressure on these species – but overfishing is by far the biggest threat, and relative fishing pressure (which takes populations into account) has increased 18-fold since 1970 , according to the study.

Sharks in particular are fished for their meat, fins, gill plates and liver oil – they were hunted so much during the peak of overfishing in the early 2000s that between 63 million and 273 million sharks were killed. every year, according to the study.

In Asia, shark fin is a prized ingredient for shark fin soup, long regarded as a status symbol at Chinese dinners and banquets. A 2018 study published in the journal Marine Policy found that in Hong Kong, “the world’s largest shark clearinghouse,” shark fin imports have doubled since 1960.

Sharks are also particularly vulnerable to overexploitation due to their low population growth rates and long generation times – in some shark species it can take several years, or even decades, between the birth of an individual and the birth of his first offspring. Rays, too, have experienced rapid depletion and local extinction due to overfishing in their historic habitats.

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There are encouraging signs for specific species – the white shark, which experienced a population collapse in the 20th century, is now showing signs of recovery in several regions thanks to bans and government policies, according to the report. Hammerhead sharks are also rebuilding their populations in the Northwest Atlantic, due to strict quotas in US marine territories.

However, the threat of overfishing far exceeds any trade regulations or sustainable fisheries management, the researchers warned.

Few countries have imposed specific catch limits on oceanic sharks, and fewer have been able to rebuild populations that have been shattered by overfishing over the past century. Although governments have signed international treaties, weak implementation has failed to effectively restrict trade or retention in these species, according to the report.

“We can see the alarming consequences of overfishing in the ocean through the dramatic decline of some of its most iconic inhabitants,” said Nathan Pacoureau, lead author of the article.

“This is something that policymakers can no longer ignore. Countries should work towards new international protections against sharks and rays, but can start immediately by fulfilling obligations already agreed at the international level.”

The study called for immediate reform to “prevent the collapse of shark populations” and the potentially disastrous consequences for their ecological systems.

Specifically, the researchers called on governments to adopt catch limits for oceanic sharks that can support sustainable fishing, and to ban the retention of sharks or rays – actions that are crucial to saving these declining populations “before let exhaustion reach a point of no return.

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