Tide begins to turn on declining NW Atlantic shark and ray populations: study
A new study has found that improved fisheries management and conservation measures are turning the tide on declining shark and ray populations in the northwest Atlantic.
The findings show how well-enforced governance coupled with science-based catch limits can help marine life recover, concluded the study, published last week in the journal Proceedings of the National Academy of Sciences.
Lead author Nathan Pacoureau, from Simon Fraser University in British Columbia, said three species have halted declines and six species are rebuilding their numbers, including great whites, hammerheads and tiger sharks. The study focused on 26 threatened species ranging from Newfoundland and Labrador to Uruguay. There are around 1,200 species of sharks and rays worldwide.
“We’re trying to take a look at the few bright spots that we have and highlight how conservation and management actually work when implemented,” he said.
He attributed the population increase to the implementation of a 1993 U.S. Atlantic shark fisheries management plan that was developed in response to increased demand for shark meat and fins. Those rules include catch reporting requirements, quotas and bans on some species, he said.
Before the 1990s, the study says, commercial and recreational fishermen were encouraged to fish for sharks, leading to severe impoverishment of some large coastal sharks.
Shark and ray populations worldwide have declined by up to 71 percent over the past 50 years, with nearly a third of the animals threatened with extinction.
But Pacoureau said stronger enforcement of vessel permits, along with a quota on how many species can be harvested, has helped numbers recover.
Co-author John Carlson said regulating catch limits, bans on certain species and enforcing the rules will help populations recover.
The 1993 plan, which has been updated over the years, is evidence of a partnership between industry, regulators and scientists, said Carlson, who is a fish biologist with the US National Oceanic and Atmospheric Administration.
“It’s a combination,” he said. “Industry has worked with us…we have better science and better data that has allowed us to create more accurate assessments.”
Different shark species differ in their life history and timing of reproduction, making populations difficult to manage, he noted.
“Some reach sexual maturity by two years. Some reach sexual maturity by the age of 20. Obviously you want to handle these a little differently based on what science is telling us.”
The dusky shark, for example, does not reach sexual maturity until the age of 20 and gives birth to one child every two or three years, Carlson said. So the dusky sharks have seen population stabilization but have yet to recover, he added.
While shark populations have increased along the Northwest Atlantic, they still face the threat of overfishing in global waters, the study found.
“We are now in a critical decade in which the future of fisheries and the world’s oceans will be determined not only by the expansion of protected areas, but also by our ability to effectively assess and sustainably manage fisheries in the rest of the ocean,” it was said .
Carlson said international engagement and collaboration is the best way to help sharks and rays.
“There are species that we share across borders. Sharks know no boundaries, they swim across them.”
Pacoureau said a number of countries have made commitments on biodiversity and agreements on fisheries and catches.
“The problem is that they sign these contracts but don’t actually implement them,” he said. “The first is that countries should honor their commitments and actually do what they say.”
—Hina Alam, The Canadian Press
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