The shark research department of the Virginia Institute of Marine Science may not have its scientists jump in the water and race against great whites for national television, but it has plenty of other exciting research projects in the works.
Robert Latour, the head of shark research for VIMS, said most sharks won't swim up into the York River, but they are nearby. The Chesapeake Bay is an important pupping ground and nursery for sandbar sharks, a protected species whose individuals can live for 30 to 40 years, migrating back to the area regularly throughout their lives. The researchers said they also encounter Atlantic sharpnose sharks, blacktip sharks, blacknose sharks, spinner sharks, tiger sharks, sand tiger sharks, dogfish sharks and a declining number of dusky sharks.
Latour said even though sandbar sharks seem to have such long lifespans in which to reproduce, females don't mature until they're between 12 and 14 years old, and with gestation periods somewhere between 9 months and a year (alternated with a year or two of rest between litters), sharks cannot rapidly bring their population numbers back up from overfishing. He said a female can maybe have 40 to 50 pups in her lifetime.
"The sharks fulfill an important role in the ecosystem," Latour said. "They're the top predators, they add stability to the food web, they add stability to the marine ecosystem so their removal or their loss is problematic on multiple fronts."
This division of William and Mary has been among the frontrunners in East Coast shark research since John "Jack" Musick started its longline shark survey project in 1973. The project, which is one of the longest-running shark surveys in the country, sets out strings of buoys attached to ropes of baited hooks that sit on the bottom of several areas of the Chesapeake Bay and other Virginia waters. The researchers take special care to use the same lines and hooks, set these rigs in the same places, visit them around the same time on the same months, use the same bait and fish the lines for exactly four hours on every observation.
James Gartland, who leads the survey, said teams go out for about five days each month, June through September. They are keeping longline setups in the places Musick started them, and are expanding to some locations north of the mouth of the Chesapeake Bay. The department conducts surveys almost constantly during the summer, Gartland said, pointing out a truck pulling away from the VIMS complex to conduct a juvenile shark survey on the Eastern Shore Monday during an interview.
Cassidy Peterson, who is pursuing her doctorate while working with the department, said the duration of the survey is uniquely valuable for studying different generations of sharks, since they live so long.
Peterson has spent the last two years combining this survey data with several other southeastern coastal surveys to take a more comprehensive look at the size of shark populations in these waters. Her paper, which argued most of the populations of the included shark species were on the rise, was published in the "Fish and Fisheries Journal" in February.
"When you think about how many fish are in the sea, it seems like such a simple question," Peterson said. "If you think about, 'How many lions are in Africa,' you can go to Africa where they live and drive around, and … if you cover enough ground, eventually you'll approximate the number of lions that are in Africa.
"Of course with fish, we can't do that. We go to where they live, and all we see is ocean," she said. "There's this third dimension of depth that we don't think about, and there's so many fewer geographic barriers to where they can move. So what we do is, we do these fishery-independent surveys as a way to look at relative abundance. If we catch more fish one year than we do the past year, then we have an idea that in this area that we're sampling, the population of that species has increased."
Here's the good news: they've been catching more sharks.
Peterson said it was heartening to see the shark populations increasing, but she definitely didn't have an answer to when they would be back to safe numbers.
"A lot of people talk about how much shark populations have declined relative to unfished levels," Peterson said. "We're not trying to get sharks back to unfished levels, we're just trying to get them to a population size that is sustainable for the long run."
The department also tags and releases sharks they encounter, and use the data that people send them back about the shark to help determine age, growth rate and migratory patterns for these animals. Gartland said the department has tagged more than 8,500 sharks since 1981.
The scientists are working on creating models to compare the size of a shark to its age, because without a reliable model, the only way to age a shark is to examine a thin cross section from a shark's vertebrae, where — similar to trees — there will be light and dark rings to correspond to the different rate the shark grew in warm summers and cold winters. Two rings indicate one year, but it's not possible to examine these until the shark is dead.
Fisherman are allowed to catch and retain some sharks, but the guidelines around fishing them are complex, especially because the species can be difficult to distinguish unless a person has had extensive experience with these animals.
"When in doubt, you should throw it back," Latour said. "If you catch a shark in the bay, the likelihood is, it's going to be a sandbar shark. The birthing period is late May to early June, so if you start seeing 50 centimeter, 45 centimeter, 70 centimeter sharks it's likely a newly pupped sandbar."
Some sharks breathe by having moving water run over their gills, rather than pumping the water through themselves, so Latour said it was important to remove the hook from a captured juvenile shark's mouth with pliers and get them back in the water as quickly as possible.
More about Virginia's sharks
Adult shark surveying: vims.edu/research/departments/fisheries/programs/sharks/programs/longline/index.php
Juvenile shark surveying: vims.edu/research/departments/fisheries/programs/sharks/programs/coastspan/index.php
Tagging program: vims.edu/research/departments/fisheries/programs/sharks/programs/tagging/index.php