Photos taken by SCUBA divers on popular reefs and wrecks off the coast of North Carolina over the last decade have helped researchers from Duke University identify individual members of the sand tiger shark population who return to these sites on a regular basis.
The photos, many of which were submitted as part of the SpotAShark USA program through the North Carolina Aquariums, dated back to 2007. Sand tiger sharks have a unique pattern of brown spots on its skin that acts like a fingerprint. Through the identification of the specific sharks shown in the photos, the researchers were able to illustrate “site fidelity” among the species over a long period of time, especially when it came to mature female sand tigers.
“Having photographic evidence that these wrecks form an important habitat the sharks return to from time to time gives us a focal point for ongoing research so we can better understand how the species is faring,” visiting scholar at the Duke University Marine Laboratory in Beaufort, North Carolina and lead author of the study Avery Paxton said.
“We’re now trying to figure out why they return. They could be using the wrecks as rest stops along their migratory paths, but they could also be returning here for mating or possibly to give birth. There are all kinds of hypotheses our team is testing.”
“This area is called the Graveyard of the Atlantic for a reason—it has hundreds of wrecks. As researchers, we can’t have eyes underwater at each of them,” Paxton said. “Being able to rely on scuba divers and other citizen scientists who are out there and have cameras with them extends our reach.”
The findings, which were published in this month’s edition of Ecology, are the first recorded instances of site fidelity in the area and support behavior that has been recorded in other locations such as in Australia and Africa and in estuarine habitats such as Delaware Bay. The researchers hope that continued efforts by citizen scientists might lead to further revelations when it comes to shark research efforts.
“By increasing community engagement, we are creating stronger connections to local, regional and global concerns for sharks and healthy ocean ecosystems,” said Hap Fatzinger, director of the North Carolina Aquarium at Fort Fisher and a co-author of the study.