News Scientists find ‘alarming’ global decline in sharks and rays
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Scientists find ‘alarming’ global decline in sharks and rays

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Nearly three-quarters of the world’s shark and ray species are heading towards extinction following an ‘alarming’ drop in numbers in the past 50 years, a new study has shown.

Despite Australia recording a 90-year high in shark fatalities in 2020, the study published in Nature journal uncovered a 71 per cent decline in shark and ray numbers.

The researchers from Simon Fraser University in Canada identified overfishing as the main cause in the ocean creatures dying away since 1970.

James Cook University’s Dr Cassandra Rigby said the high number of shark attacks in Australia was not an indicator that populations were thriving.

“We’ve got 1200 species of sharks and rays in the world and those responsible for attacks are just a couple of species.”

Using a model based on biodiversity indicators, scientists found the number of sharks and rays caught compared to the total population of these animals has had an 18-fold increase over the same period.

The team analysed 18 shark species and found the oceanic whitetip shark, the scalloped hammerhead and the great hammerhead were critically endangered.

“The global abundance of oceanic sharks and rays has fallen to the point that 75 per cent of these species now qualify as threatened with extinction,” said Dr Rigby.

“The alarming trend is that there has been this decline, and that is even maybe more severe than we think because we only started looking at analysis about 1970.

“These open ocean fishing fleets have been expanding globally since before the 1950s.”

The clear driver of the “alarming” trend was a doubling of fishing pressure and a tripling of shark and ray catches, the team of researchers from universities around the world concluded.

The scientists urged governments worldwide to act fast to prevent the extinction of huge numbers of shark and ray species, for example by introducing upper limits to fishing, so that numbers could be recovered.

Despite poor outlooks for many other species, great white sharks and the great hammerhead shark populations in the Northwest Atlantic Ocean appeared to be recovering due to strict US laws now protecting them.

Similar protections, including science-based fishing limits, are urgently needed across to globe to prevent shark and ray population collapses, Dr Rigby said.

“I hope it is a call to action. We can’t just sit back and do nothing.”

Eight Australians were killed in shark attacks in 2020, the highest number since 1929.

The paper, published on Thursday, is part of the Global Shark Trends Project, which is reassessing the population of 1200 species around the world and marks the first global analysis of its kind, the authors say.

-with AAP