Shark and ray populations rebounding in Northwestern Atlantic: SFU study

January 25, 2023
Photo: Hannes Klostermann

Better fisheries management and conservation is effective at turning the tide on the shark and ray declines, according to a study from Simon Fraser University researchers.

The fact sharks and rays are increasingly threatened by overfishing has made global headlines in recent years.

Oceanic populations have plummeted by as much as 71 per cent in the last 50 years and one third of all sharks and rays are threatened with extinction.

But there is hope, and proof that the declines can be reversed, according to a new study published this week in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Lead author Nathan Pacoureau, postdoctoral research fellow at SFU, and colleagues analyzed trends in fishing pressure, fisheries management, and population status for all wide-ranging coastal sharks and rays that occur in the western Atlantic Ocean.

They found that populations in the northwest Atlantic recovered following implementation of a U.S. fishery management plan for sharks of the Atlantic Ocean in 1993.

Declines have been halted in three species and six species of eleven are clearly rebuilding now. This recovery has been achieved by regulation, enforcement, and monitoring.

A strong system of regulations has been put in place for these species, including catch reporting requirements, aggregate- and species-specific quotas, and catch prohibitions for some species.

Management is strongly enforced by US Coast Guard and law enforcement agencies, and the government continues to monitor and assess fisheries with additional regulations when needed.

“Our findings provide hope, but are a microcosm of the wider problem faced by sharks and rays,” says Pacoureau. “Many shark and ray species range widely and successful conservation in one country can be undone by less regulated fishing areas outside those borders.”

Using the International Union for Conservation of Nature (IUCN) Red List Index, the team showed how populations of the same species had collapsed in the southwest Atlantic due to unrestrained fishing.

The current number of wide-ranging coastal species threatened with extinction is almost four times lower in the northwest than that in the southwest Atlantic.

“These sensitive species have very slow life histories and are often collateral damage of sustainable target fisheries for more productive species,” says SFU professor Nick Dulvy, Canada Research Chair in Marine Biodiversity and Conservation.

The findings highlight the need for well-enforced governance and science-based effective limits on fishing to prevent population collapses and to reduce extinction risk for many species.

The international study also included researchers from National Marine Fisheries Service in the U.S., James Cook University in Australia and Federal University of Ceará in Brazil.