Empty seas: oceanic shark populations plummet

A shortfin mako shark swimming in the ocean
A shortfin mako shark | Image: Greg Skomal

A new study finds a steep decline in global shark and ray numbers

For millennia, the remoteness of species oceanic sharks and rays allowed them to largely avoid humans. Since the early 1950s however, industrial-scale fishing fleets have been able to reach these distant waters. Demand for shark and ray meat, as well as fins, gill plates and liver oil, has caused catches to soar.

dead dhortfin mako sharks for sale
Shortfin mako sharks for sale | Image: José Antonio Gil Martínez, CC

New research published in Nature shows that oceanic shark and rays have declined by an incredible 71% since 1970. The study attributes the decline to overfishing however, unreported catches weren’t included in the study’s analyses. Illegal fishing vessels often specifically target sharks. Illegal shark finning alone is conducted on an industrial scale, suggesting an underestimate of the drop in numbers.

shark fins drying in the sun somewhere in Asia
Demand for shark fins in traditional cuisines throughout Asia has soared in recent decades. Image: EPA/Alex Hofford

Sharks and rays produce few offspring and grow slowly, no match for current levels of industrialised fishing. Since most oceanic sharks and rays are caught in the high seas – areas beyond national jurisdictions – agreements between fishing nations within management organisations are needed for conservation measures to work.

One solution would include modifying fishing gear and improving how fishers release sharks and rays after capture, to give them a better chance of survival. An equally important measure would be banning fishing fleets from hotspots of oceanic sharks and rays. Research published in 2019 highlighted where these areas in the global ocean overlap with fishing vessels most.

Longline fishing hooks
Longline fishing deploys several hooks at once | Image: Lunghammer/Shutterstock

Led by the UN, negotiations are underway for a high seas treaty which would create no-take marine reserves to protect threatened species in the open ocean. This new study should urge the international community to take such action while there’s still time.

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