Researchers made the remarkable find — one among several such finds they have made in these waters over the last four years — by using acoustic tags, Science Daily reports. The tags are devices that allow scientists to track marine animals remotely as they move through their environment. The data played a key role in helping the scientists discover the nursery. A mere handful of sand tiger nurseries have been identified, including one which is located in the waters around Massachusetts.
The discovery of this nursery is great news for conservationists hoping to learn more about sharks and other species within the area, Jon Dohlin, Vice President and Director of the Wildlife Conservation Society’s New York Aquarium said, in a statement.
“Through field projects and outreach efforts by the New York Aquarium and other organizations, we hope to raise awareness about our local marine environment and the need to manage our natural wonders,” he said.
In 2011, the researchers realized there might be a nursery ground in Great South Bay when one scientist received a photo of a dead juvenile sand tiger shark from a local marina. In subsequent conversations with local fishermen and boaters, it was revealed that people had been catching these small sharks in the bay for a number of years.
That’s when the scientists began using acoustic transmitters to tag the sharks. They have been catching and releasing the young sharks ever since. There were 15 sharks tagged this year, 10 of which hadn’t been tagged before, while five individuals had, in fact, been tagged in previous years, returning to the same section of the bay in a behavior that’s known as “site fidelity.”
The data helps track the sharks’ movements, and this is helping scientists learn about their migratory behavior and their habitat needs. The discovery of the shark nursery in Great South Bay is crucial, the statement noted, because sand tiger shark numbers have been heavily depleted by fishing and they are listed as a “Species of Concern” by the U.S. National Marine Fisheries Service. And, since 1997, fishing for these sharks has been prohibited in state and federal waters.
These sharks also have a slow reproductive rate. Females only give birth to one to two pups every two years, and this means it will take this population several years to rebuild. Keeping the nursery protected will help promote recovery for sharks living in the coastal waters of the eastern U.S.
“Sand tiger shark pups are not born here but migrate from down south to spend the summers as juveniles in New York’s coastal waters,” said Dr. Merry Camhi, director of NY Seascape, the WCS’s local marine conservation program, The New York Daily News reports. “The acoustically tagged animals in our study will help us better understand where the sharks go, their habitat needs and how we can better protect them.”
Nurseries like the one at Great South Bay provide juvenile sand tiger sharks (ranging in age from several months to five years old) with a place to feed and grow. Here, they can also find protection from predators–including other sharks, Science Daily reports. These sharks are found in all warm, coastal waters, and give birth to live young. Once they are born, juvenile sharks migrate north in the spring and hangout in New York waters during the summer. In the fall, they head south.
These usually non-aggressive sharks can grow up to 10 feet long and weigh as much as 350 pounds.
They are listed as “vulnerable” by the International Union for Conservation of Nature and Natural Resources (IUCN).
There are still many questions to answer regarding these newly discovered New York residents. “How many sand tiger sharks migrate to the Great South Bay each summer?” and “Once they get there, what do they eat?” are just two of the questions researchers want to answer.
Arkive reports that these sharks mate between October and November. Courtship can take a while, and the male aggressively nips potential mates. The pups grow inside their mother for nine months to one year. Females have two oviducts, each with thousands of eggs, and the one to two pups that are born feast on the eggs and their siblings. Once they are born, the little sharks measure up to one meter in length.
During the day, sand tiger sharks (Carcharias taurus) prefer to hang out near caves and ledges, hovering by themselves or in small groups. While those spiky teeth look scary, they feed mainly on fish.
However, this species’ situation is quite precarious because they are vulnerable to overfishing, especially since they have a low reproductive rate. Although they have a widespread distribution, their populations are isolated, and available data show that the species is likely in decline. In Japan, their meat is prized. Oil from these fish, as well as their fins, are in demand. During the 18th and 19th centuries the shark was hunted relentlessly for its liver oil, which was used for lighting. And since sand tiger sharks like to congregate in coastal areas at certain times a year, it makes them especially vulnerable to fishing.
Even though they are protected in countries like Australia and the United States, management plans need to be developed in order to safeguard the future of these magnificent sharks, Arkive reports.
