SHARK, RAY POPULATIONS HAVE DROPPED 70%, STUDY WARNS

Some species of sharks and rays could disappear from our seas altogether after a sharp drop in their numbers due to overfishing in the past 50 years, Jessie Yeung reported for CNN late.

A study published Wednesday in the journal Nature found that shark and ray populations fell by 71.1% from 1970 to 2018. "Knowing that this is a global figure, the findings are stark," said Nick Dulvy, a biologist at the Simon Fraser University and a co-author of the study.

"If we don't do anything, it will be too late. It's much worse than other animal populations we've been looking at."

Of all 31 species of oceanic sharks and rays, 24 are now threatened with extinction, several of which are classed as critically endangered -- the highest threatened category.

"It's an incredible rate of decline, steeper than most elephant and rhino declines, and those animals are iconic in driving conservation efforts on land," Dulvey said.

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

The study urged immediate reform to "prevent shark population collapses" and the potentially disastrous consequences for their ecological systems.

Specifically, researchers called on governments to adopt catch limits for oceanic sharks that can support sustainable fisheries, and bans on shark or ray retention -- actions that are crucial to saving these shrinking populations "before depletion reaches a point of no return."

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