December 28, 2020 — In the coastal waters of the mid-Atlantic, an endangered shark is making a comeback. Led by former Smithsonian postdoc Chuck Bangley, scientists at the Smithsonian Environmental Research Center (SERC) tagged and tracked nearly two dozen dusky sharks over the course of a year as part of the Smithsonian’s Movement of Life Initiative. They discovered that a protected zone put in place 15 years ago is paying off — but with climate change, it may need some tweaking.
Dusky sharks are what Bangley calls “the archetypal big, gray shark.” Born 3 feet long, as babies, they’re already big enough to prey on some other shark species. But they’re slow-growing. It can take 16 to 29 years for them to mature. If their populations take a hit, recovery can take decades.
An endangered species, duskies aren’t very common in Delaware waters. When they do surface, they’re easily mistaken for sandbar sharks. But in this new study, the Smithsonian tracked dusky sharks swimming past the southern tip of Delaware on their migrations up and down the Atlantic. For conservationists, it’s a sign that protections put in place are slowly starting to pay off.
The sharks’ numbers plummeted in the 1980s and 1990s, when well-intentioned managers offered sharks as an “alternative fishery,” while other stocks, like cod, were collapsing. The overfishing that followed wiped out anywhere from 65% to 90% of the Chesapeake’s duskies, said Bangley, now a postdoc at Dalhousie University in Nova Scotia. Managers banned all intentional dusky shark fishing in 2000. Five years later, they created the Mid-Atlantic Shark Closed Area along the North Carolina coast. The zone prohibits bottom longline fishing, which can ensnare dusky sharks, for seven months of the year.