Shark and ray populations recover in the Northwest Atlantic

Newswise — Better fisheries management and conservation is effective in turning the tide of shark and ray declines, according to a study by Simon Fraser University researchers.

The fact that sharks and rays are increasingly threatened by overfishing has made world news in recent years.

Ocean populations have plummeted by as much as 71 percent in the past 50 years, and a third of all sharks and rays are threatened with extinction.

But there is hope and evidence that the decline 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 (PNA).

Lead author Nathan Pacoureau, a postdoctoral researcher at SFU, and colleagues analyzed trends in fishing pressure, fisheries management, and population status of all wide-ranging coastal sharks and rays found in the western Atlantic Ocean.

They found that populations in the northwest Atlantic rebounded following the implementation of a United States fisheries management plan for Atlantic Ocean sharks in 1993.

Declines have halted in three species and six species out of eleven are now clearly recovering. This recovery has been achieved through regulation, enforcement and control.

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

The US Coast Guard and law enforcement agencies strictly enforce the management, and the government continues to monitor and evaluate the fisheries with additional regulations where necessary.

“Our findings provide hope, but they are a microcosm of the broader problem facing sharks and rays,” Pacoureau says. “Many shark and ray species are widely distributed and successful conservation in one country can be undone by less regulated fishing grounds 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 rampant fishing.

The current number of endangered wide-ranging coastal species is almost four times lower in the Northwest than in the Southwest Atlantic.

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

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

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