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Changes in Extinction Risk Give Insight into Marine Biodiversity

Simon Fraser University scientists are part of an international group of researchers who have devised a new science-based indicator to evaluate the state of the oceans—and the potential risk of extinction of their species.

Changes in Extinction Risk Give Insight on Marine Biodiversity

Image Credit: Ethan Daniels/

The latest biodiversity research indicates an alarming loss of species, ecosystems, and genetic diversity on land, but it is unknown how prevalent similar patterns are in the oceans.

Scientists from Spain’s AZTI Technology Centre, in partnership with SFU and the International Seafood Sustainability Foundation (ISSF), established a global indicator that evaluates the state of marine biodiversity based on changes in extinction risk documented in oceanic predatory fishes (52 populations of 18 different species of tuna, billfish, and sharks) over 70 years in research published recently in the journal Science.

The research suggests how, since the 1950s, the worldwide extinction risk of oceanic predatory fishes has steadily increased owing to overfishing until the late 2000s.

The results suggest that there is still room for improvement in the management of sharks accidentally caught by the same fisheries despite the global rebuilding of commercially significant tuna and billfish species. This emphasizes the need to take action to reduce the sharks’ rising risk of extinction.

Subsequently, management techniques implemented by international fisheries groups considerably lowered fishing mortality, allowing tunas and billfish to recover. Nevertheless, the danger of extinction for undermanaged sharks is increasing.

It’s encouraging to see we’ve been able to halt declines of tunas and billfishes but the decline of sharks continues. If we don’t do anything to mitigate overfishing and lack of effective management, the loss of these species threatens the balance of ecosystems and risk of food security and jobs in both developed and developing countries.

Nick Dulvy, Distinguished Professor and Canada Research Chair, Marine Biodiversity and Conservation, Simon Fraser University

The researchers believe that shark fisheries management can mimic the success of tuna and billfish fisheries management. According to them, marine sharks desperately require better management and protection from overfishing. This can be accomplished by restricting trade, resetting priorities in international fisheries bodies, and establishing explicit biodiversity goals and targets.

According to the research, establishing science-based capture limits and modifying how and where gear is deployed can help to avoid and reduce incidental shark catching. The CITES summit in Panama provides a unique opportunity to regulate 90% of the worldwide shark fin trade.

Journal Reference:

Juan-Jordá, M. J., et al. (2022) Seventy years of tunas, billfishes, and sharks as sentinels of global ocean health. Science.


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