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Around one-third of the sharks killed between 2012 and 2019 belonged to species facing extinction, study authors say.

"The number of threatened shark species around the world keeps going up, not down. So we need to do more," Dalhousie University biology professor and the study's lead author, Boris Worm, said in an interview.

While some regulations around the world have successfully reduced shark mortality, increased deaths in other areas of the globe have offset that progress, he explained.

"But we see some signs of hope that if you actually address mortality, not just finning, you can bring mortality down," he said.

Until now, no study had examined the effectiveness of measures to combat finning. Worm and other researchers examined shark mortality in the waters off 150 countries where the animals are fished, and deaths in open-ocean environments.

They found that coastal fishing was responsible for 95 per cent of all sharks caught and killed between 2012 and 2019. Mortality in these fisheries increased by four per cent in that time period. Meanwhile, mortality declined by seven per cent in offshore fisheries, especially in the Atlantic and western Pacific oceans.

Shark fins are highly prized in certain markets, particularly in Asia. While the crackdown on finning appears to have reduced the practice, it may have had the perverse effect of opening new markets for shark meat, study authors say. Now forbidden to harvest only fins, fishermen may be incentivized to sell the whole animal.

The researchers note an increase in demand for shark meat in countries such as Brazil and Italy. Because shark is a cheap substitute for other fish, study authors point out, the meat is often mislabelled and likely consumed unknowingly.

"We see these emerging markets for shark meat and shark oil and other shark products where we didn't see them before," study co-author and Carleton University post-doctoral fellow Laurenne Schiller said in an interview. "It really speaks to the fact that if you're going to implement a regulation, you have to think about the potential for unintended consequences."

Highly effective measures to protect sharks are rare, the authors say. One such measure, Worm said, is a complete ban on their fishing. Another is strict regulations for fisheries to protect threatened species. Such a measure is already in place in Canada, where harvesters must release endangered species alive whenever possible, he explained.

Fisheries can also phase out indiscriminate fishing methods, for example by replacing equipment that catches sharks by mistake with gear that is more selective.

"If you look at shark health in any ecosystem, it's a really good indicator of how healthy that marine environment is," Schiller said. "When we see this level of mortality and we see what's working but also where we still need to … focus, we can think more critically about our role as humans in the protection of these species to hope for more resilient ecosystems into the future."

This report by ºÃÉ«tvwas first published Jan. 11, 2024.