- Effective fisheries management, strong regulations, enforcement, and monitoring can help conserve sharks and rays, according to new research.
- Researchers found that some shark populations in the northwest Atlantic recovered after the U.S. implemented a management plan in 1993, despite ongoing fishing, while populations in areas without sufficient management declined.
- A previous study found that overfishing threatens one-third of sharks, rays and chimeras with extinction, making them the second-most endangered vertebrate group, after amphibians.
New research has found that carefully managed fisheries can help dwindling shark and ray populations recover, illustrating a pathway for protecting species from fishing pressure.
Published in the Proceedings of the National Academy of Sciences, the study analyzed several decades’ worth of trends in fishing pressure, fisheries management, and population status of 26 shark and ray species found in the western Atlantic. It determined that some shark populations in the northwest Atlantic bounced back after the U.S. implemented a management plan in 1993, while shark populations in areas without sufficient management often declined.
For instance, the study found that the white shark (Carcharodon carcharias) population in U.S. coastal waters experienced annual declines of about 0.07% between 1961 and 1993. But after the establishment of the management plan, white sharks began to increase by 0.1% each year, despite ongoing fishing pressure. Other shark species have also mounted recoveries following the U.S. management plan, including tiger sharks (Galeocerdo cuvier), scalloped hammerheads (Sphyrna lewini), great hammerheads (S. mokarran), bonnethead sharks (S. tiburo) and dusky smooth-hounds (Mustelus canis).
However, many of these same species are not faring as well in other parts of the western Atlantic where fisheries management plans are not in place to protect sharks from overexploitation, or there is a lack of regulations and monitoring, according to the research.
The authors suggest that the recovery of sharks in U.S. waters was not only due to the introduction of the management plan, but a robust system of regulations, constant monitoring, and the enforcement of rules by the U.S. Coast Guard and other law enforcement agencies.
“With this paper, we wanted to send a message that you can actually recover and rebuild your shark populations [with management],” Holly Kindsvater, study co-author and scientist at Virginia Tech’s Department of Fish and Wildlife Conservation, told Mongabay. “But it’s not easy, and it requires some capital and real attention and engagement from governments.”
Kindsvater noted that while the U.S. manages its sharks well in its territorial waters, it imports more seafood than it catches domestically. She said the U.S. is therefore responsible for ensuring that its imported seafood comes from adequately managed fisheries.
“If the US market were to demand sustainability … it would strongly motivate the enforcement of national plans of action that places like Brazil do have in place [but are] not committing budgetarily to yet. Or if they have, it hasn’t shown up in the data,” she said.
While the study illustrates that well-managed fisheries can help sharks recover, global shark populations are in peril. A 2021 study in Current Biology found that one-third of sharks, rays and chimeras are threatened with extinction, making them the second-most endangered vertebrate group, after amphibians. Another study published this year in Nature Communications found that half of shark and ray species that inhabit coral reef ecosystems are threatened with extinction. Both papers found a common culprit for these declines: overfishing.
Sharks are deliberately targeted for their meat and fins, and also accidentally captured as bycatch. This combined fishing pressure is responsible for the deaths of about 100 million sharks per year, according to a 2013 study in Marine Policy.
Nathan Pacoureau, the lead author of the PNAS study and co-author of the two other studies on threatened shark species, said a primary reason for global shark declines is a lack of fisheries regulations and enforcement.
“A lot of countries sign international treaties that [include] regulations for fisheries, but they actually don’t implement them,” Pacoureau told Mongabay. “So that’s a problem.”
He said he believes successful fisheries management will depend upon transferring knowledge and capacity to countries where shark and ray numbers are declining to “help them transition to sustainability.”
Luke Warwick, director of shark and ray conservation at the Wildlife Conservation Society, who was not involved in the PNAS study, said the findings were “encouraging,” but raised a fundamental issue: effective fisheries management seemed to only exist in wealthy nations.
“The only good examples … of effective fisheries management of stabilizing and then recovering shark populations come from [countries like] the United States and Australia,” Warwick told Mongabay. “And that’s a huge problem because the places where we’re going to see the extinction of sharks in the coming decades — unless we radically change things — is mainly in the global tropics, in resource-poor countries, where the type of management showcased in the study just isn’t feasible.”
Banner image: A southern stingray in the Caribbean Sea. Image by Gregory Piper / Ocean Image Bank.
Elizabeth Claire Alberts is a senior staff writer for Mongabay. Follow her on Twitter @ECAlberts.
More than half of reef sharks and rays threatened with extinction, study shows
Citations:
Pacoureau, N., Carlson, J. K., Kindsvater, H. K., Rigby, C. L., Winker, H., Simpfendorfer, C. A., … Dulvy, N. K. (2023). Conservation successes and challenges for wide-ranging sharks and rays. Proceedings of the National Academy of Sciences, 120(5). doi:10.1073/pnas.2216891120
Dulvy, N. K., Pacoureau, N., Rigby, C. L., Pollom, R. A., Jabado, R. W., Ebert, D. A., … Simpfendorfer, C. A. (2021). Overfishing drives over one-third of all sharks and rays toward a global extinction crisis. Current Biology, 31(21), 4773-4787.e8. doi:10.1016/j.cub.2021.08.062
Sherman, C. S., Simpfendorfer, C. A., Pacoureau, N., Matsushiba, J. H., Yan, H. F., Walls, R. H., … Dulvy, N. K. (2023). Half a century of rising extinction risk of coral reef sharks and rays. Nature Communications, 14(1). doi:10.1038/s41467-022-35091-x
Worm, B., Davis, B., Kettemer, L., Ward-Paige, C. A., Chapman, D., Heithaus, M. R., … Gruber, S. H. (2013). Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy, 40, 194-204. doi:10.1016/j.marpol.2012.12.034
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