Citizen scientists help find evidence of shark-shipwreck connection

(Source: North Carolina Aquariums)
(Source: North Carolina Aquariums)
Updated: Apr. 23, 2019 at 12:10 PM EDT
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PINE KNOLL SHORES, NC (WECT) - Turns out humans aren’t the only creatures drawn to shipwrecks.

According to initial findings from North Carolina Aquariums’ Spot A Shark USA program, shipwrecks are potentially critical habitat for sand tiger sharks, and could help facilitate conservation of the species.

US populations of sand tiger sharks have declined by an estimated 75 percent, primarily in the 1980s and 1990s.

Spot A Shark USA is a program that uses divers — called citizen scientists — to photograph sharks. Divers submit new and historical images to the Spot a Shark USA website, and researchers map the spots of each shark to identify them uniquely, much like a human fingerprint.

“Photographs collected by citizen scientists revealed that a large coastal shark species, the sand tiger shark, returns to the same or nearby shipwrecks,” said Avery Paxton, lead researcher for the project and principal author of a four-page document that outlines the shark-shipwreck connection. “This behavior, known as site fidelity, could mean shipwrecks play a significant role in the lives of this imperiled shark species.”

North Carolina shipwrecks are used as rest stops of sorts for sharks on their journey from New England to Florida, according to the initial findings. Shipwrecks may be even more valuable to sand tiger sharks and could be key reproductive or year-round habitats.

(Source: North Carolina Aquariums)
(Source: North Carolina Aquariums)

In a manuscript published by the Ecological Society of America, a diver photographed a female sand tiger shark on a September 2016 dive at shipwreck off the coast of North Carolina.

Ten months later, the same diver returned to the same shipwreck and captured another photograph of a female sand tiger shark. The images were uploaded to the Spot A Shark USA website and software comparisons determined it was the same shark.

“Six female sand tiger sharks were photographed and re-photographed at the same or nearby shipwrecks located off the coast of North Carolina over a period of time ranging from a few months to six years,” Paxton said. “This indicates shipwrecks are potentially critical habitats for sand tiger sharks and worthy of further research.”

The Spar, Aeolus and Atlas are among the North Carolina shipwrecks mentioned in the initial findings, which are similar to research done along the eastern Australia coast and in offshore waters of South Africa.

While patterns have seemingly emerged concerning sharks and shipwrecks, Paxton said more research is needed.

“There are still a lot of unknowns,” he said. “We do not know what the female sand tigers are doing in between the times they are photographed. We also do not know what the males are doing. That does not mean that the males do not also return to the same or nearby shipwrecks, rather they have not been photographed doing so.

“It is a scientific process, and we have just started chipping at the surface. That’s why it is so important to share this information to further future research efforts.”

This research collaboration, led by North Carolina Aquariums, also includes UNCW, UNC Chapel Hill, Duke University and other schools, zoos, aquariums and conservation groups.

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