New Study Finds Shark Populations Down 71%

Photo Andy Murch

San Francisco conservation group calls for immediate cessation of shark and ray fishing.

A study published in the journal Nature this week documents an alarming worldwide decline of oceanic shark and ray populations over the past 50 years, primarily due to overfishing. The study, ‘Half a century of global decline in oceanic sharks and rays’ assessed 31 species of sharks and rays and reported a 71% decline in global abundance since 1970. Global fishing pressure doubled and a tripling of shark and ray catches occurred during the same period. 77% of oceanic shark and ray species are now considered threatened with extinction under the Red List criteria of the International Union for Conservation of Nature (IUCN).

“We demonstrate that — despite ranging farther from land than most species — oceanic sharks and rays are at exceptionally high risk of extinction, much more so than the average bird, mammal or frog,” said Dr. Nicholas Dulvy, Professor at Simon Fraser University and one of the study authors. “Overfishing of oceanic sharks and rays jeopardizes the health of entire ocean ecosystems as well as food security for some of the world’s poorest countries.”

Formerly abundant, wide-ranging oceanic sharks have declined so dramatically that they are disappearing from their range, and now fall into the two highest threat categories on the IUCN Red List. The commercially targeted Shortfin Mako Shark was recently classified as Endangered while the iconic Oceanic Whitetip Shark is now considered Critically Endangered. Manta rays have joined the group as among the most in rapid decline.

“Each new study demonstrates the urgency of extinction. We are losing biodiversity that keeps the oceans rich and healthy. This is directly related to overfishing, which includes large species of tuna which are also suffering declines. Open ocean sharks and rays are critical to the health of our marine ecosystems, and now more than ever, humans need to act for global health that includes protecting wildlife,” said David McGuire, Director of Shark Stewards and the Earth Island Institute

The study also concludes that regional tuna fisheries management organization’s fishing limits for commercially important sharks are largely inadequate with respect to heeding scientific advice and using ecosystem-based fisheries management. Sharks and rays are highly vulnerable to overfishing because they tend to grow slowly, have late onset of reproduction and produce fewer young. Sharks and rays are targeted for meat, fins, liver oil, gill plates, and for recreational fishing.

“This is an alarm bell calling for urgent protection of endangered sharks and rays,” adds McGuire. “Hammerhead sharks and manta rays could disappear in our lifetime. We are calling for an immediate end to the trade of fins and gills from all threatened and endangered sharks and rays. It is time for the world to wake up and save sharks and rays from extinction.”

Contact David McGuire

Pacoureau, N., Rigby, C.L., Kyne, P.M. et al. Half a century of global decline in oceanic sharks and rays. Nature 589, 567–571 (2021).