When scientists tagged a 12-foot tiger shark they captured off the S.C. coast last week, they were surprised to learn the ferocious predator soon would be a mom.
The tiger shark, caught and released at St. Helena Sound, is the first pregnant shark to be fitted with a satellite tracking device in South Carolina — and that’s significant, according to the S.C. Department of Natural Resources.
Being able to track a pregnant tiger shark will give the agency clues to understanding more about shark reproduction in South Carolina at a time when the species is under threat from overfishing.
“We’ve been thinking for five or so years that the southern sounds of South Carolina, especially Port Royal and St. Helena sounds, are important for mating,’ ” Natural Resources spokeswoman Erin Weeks said. “But she is really the first solid confirmation we have that pregnant sharks are using these waters.”
The satellite tag, unlike conventional tags, allows the natural resources agency to follow the shark’s movements on a regular basis.
“We’re now going to get to see how she is utilizing these waters, where she is traveling, where she might be foraging, giving birth and nursing,” Weeks said.
The shark tagged last week, nicknamed “Harry-Etta,” had been caught and tagged before but never with a satellite-tracking device. Tags like the one put on Harry-Etta are secured to shark fins. They release signals when sharks surface for more than 90 seconds.
While briefly in captivity, the shark was given an ultra sound by a graduate student studying pregnant sharks. The ultrasound showed the tiger shark was pregnant, Weeks said. Harry-Etta can expect to produce shark pups by mid-summer, according to the DNR.
“It just turned out the one they satellite tagged was pregnant,” she said.
A tiger shark can give birth to as many as 80 babies at once, according to the environmental group Oceana. The National Marine Fisheries service puts the number at more than 50.
Tiger sharks are some of the largest sharks in the ocean and have a reputation as man-eaters. Only great white sharks attack more people, according to National Geographic.
Tiger sharks, named for the stripes on their sides, can be found in tropical and subtropical waters. They can grow to 25 feet long and weigh up to 1,900 pounds.
Despite their ferocious reputation, tiger sharks are considered important to the ocean ecosystem. They are apex predators that devour other species that could overpopulate the sea. But the big sharks are hunted for their fins, skins and livers and, today, are listed as “near threatened” in much of the world, according to National Geographic.
In South Carolina, Natural Resources has tagged 15 tiger sharks with satellite tracking devices in recent years as part of an effort to better understand the movements of the big predators. The state agency has worked collaboratively with OCEARCH, a nonprofit group that began tagging big sharks, including great whites, and tracking their movements.
Following shark movements allows marine resources officials to make more informed decisions about how to protect the species, officials said. Discovering which habitats are most important to tiger sharks could one day help determine whether those areas should be protected, according to the DNR.
“When you have healthy large shark populations, you have a good healthy rest of the ecosystem,” Weeks said.
Track the shark
To learn more about the movement of South Carolina’s pregnant shark, and others, see the OCEARCH global shark tracker at http://www.ocearch.org/?utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=.