Earth’s shark and ray populations are facing a “staggering” decline, according to new research from Simon Fraser University.
The analysis, published Wednesday in the journal Nature and a part of the Global Shark Trends Project, found that global populations of sharks and rays have suffered a 71-per cent drop since 1970.
It also concluded that overfishing was a key culprit in the decline, said study co-author and Canada research chair in marine biodiversity and conservation, Prof. Nick Dulvy.
“They’re among the most evolutionary distinct and iconic animals in our oceans, and many of them are some of the top predators in our oceans,” Dulvy told Global News.
“We’ve eventually taken their place as hunters in the ocean.”
Researchers extrapolated that of 31 species of sharks and rays examined, 21 were currently facing extinction risks.
A recent study estimated that about 100 million sharks are caught each year.
According to Dulvy, the number of fishing vessels has doubled globally in the last 50 years, while the catch of sharks has tripled.
Part of that, he said, has come as a result of the push for sustainability in other major fisheries, such as the tuna catch.
Commercial fishing fleets have in some cases shifted to catching and keeping sharks, whose flesh, he said, can be quite valuable.
“(Sharks) for their fins, rays for their gills, for their livers, which are used for oil, but primarily for their meat.”
Because sharks reproduce late in life and have few offspring, Dulvy said the impact of overfishing has been particularly devastating.
Canada has taken several steps towards shark conservation, including banning the harvesting of endangered shortfin Mako sharks, and banning the import export of shark fins.
Under Fisheries and Oceans Canada regulations, recreational anglers must release any sharks they catch, as must commercial operations who land sharks as bycatch.
Commercial shark fishing quotas are “set at levels which maintain or increase population numbers at healthy levels, based on the best available scientific information,” according to the agency.
That’s a good start in Dulvy’s view, but he said more pressure is needed to prevent catastrophe for a family of animals whose lineage predates the dinosaurs.
“Many nations are not living up to their international commitments, so we’d like nations to simply deliver on what politicians have committed to in recent years,” he said.
If countries can agree to better regulate shark fishing, Dulvy said, there is reason for optimism.
The Great White Shark, which Dulvy said was unfairly persecuted in the wake of the Jaws film franchise, has seen its populations rebound on both U.S. coasts in recent years.
“If we can recover the Great White Shark, there’s no reason we can’t halt these declines and recover the other species,” he said.
— With files from Linda Ayelsworth
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