Island based DMF biologist tags great whites off Cape
On Saturday Greg Skomal, a Massachusetts Division of Marine Fisheries (DMF) biologist who lives in Oak Bluffs, led a team that included a commercial harpooner in a successful effort to tag two great white sharks off the coast of Chatham. On Tuesday they tagged three more great whites, which they estimated to be 9, 12, and 15 feet long, bringing the total to five.
Tagging one on Saturday was no small feat, even for a fish about ten feet in length weighing approximately 1,000 pounds. Tagging five was beyond anyone's expectations.
Finding great whites can be difficult. Getting close enough to hit one with a harpoon in order to imbed a tag requires equal measures of luck and skill. Bill Chaprales, a commercial harpoon fisherman from Cape Cod, helped the biologists develop the techniques they needed to locate and get close to the fish, and use a harpoon to plant a tag that would remain in a free-swimming fish.
Mr. Skomal surveyed the waters off Chatham by air last Thursday after receiving reports of five sharks swimming off the southeastern tip of Monomoy Island, where they had likely been attracted by a large population of seals. He soon confirmed the presence of at least one great white.
He returned by boat over the weekend, assisted by a private spotter pilot, George Breen. Saturday was only the second time a great white was successfully tagged in the Atlantic off the U.S. coast.
On September 21, 2004 a female great white shark estimated at 14 feet long and 1,700 pounds was discovered swimming in a deep, narrow inlet in the Elizabeth Islands chain just west of Woods Hole.
Mr. Skomal and his colleagues made history when Mr. Skomal successfully implanted a small pop-up archival tag into the shark. But their excitement soon faded when the tag malfunctioned and detached prematurely.
The computerized tagging devices used by Mr. Skomal over the last several days are programmed to detach on January 15, 2010. If all goes well they will then transmit stored data via a satellite back to researchers, providing new information about the movements of a species that scientists have rarely tracked in the Atlantic.
For Mr. Skomal, the state's shark expert, the past week has been personally and professionally exciting. On Monday, The Martha's Vineyard Times reached Mr. Skomal by telephone in the cockpit of a boat off Chatham while he was ladling ground-up fish, called chum, into the water in an effort to attract a great white.
Mr. Skomal resorted to chumming after trying to chase fish down. "They are very quick and elusive," he said.
Mr. Skomal said he had probably seen over a dozen great whites. "But the bigger question is, are we seeing the same ones over again," he said. The sharks were dispersed over a broad area from the southern tip of Monomoy to Chatham Harbor and Nauset Beach. "Sharks have been sighted all along that area generally within a mile of the beach."
In response to reports of great whites so close to Chatham, town officials decided to ban swimming indefinitely at four popular beaches.
Mr. Skomal said there was nothing unusual in the appearance of sharks in Cape waters. "If there is a healthy seal colony that offers them a predictable source of food then they are going to start hitting it, and that is exactly what is happening," he said. "The unusual part is we have not documented a lot of that kind of activity in the Atlantic until now."
Mr. Skomal said the biology of great whites in the Atlantic is poorly understood, particularly in terms of seasonal movements. The tags are expected to help answer some of those questions.
Mr. Skomal has been looking forward to another opportunity to tag a great white since 2004. "Since the tag failed I've been gnawing at the bit to get more of these out," he said. "I didn't dream I'd have an opportunity to tag multiple sharks in this area. It is an amazing experience."
The hope is to learn more about the residency patterns of these fish in New England waters - when they arrive, when they depart and where they spend the winter months, something that is largely unknown.
There is not a lot known about the size of the North Atlantic population or its habits and ecology, according to Mr. Skomal "That is what I hope these tags will begin to answer," he said.
Assisting Mr. Skomal Tuesday was DMF biologist John Chisholm and Jeff Kneebone, a student assistant from the University of Massachusetts. A private boat owner had donated his boat and its captain, Ron Crisp.
"This is extremely exciting for me," Mr. Skomal told The Martha's Vineyard Times. "I am ecstatic about what we've gotten out, and what I hope we can still get out. The presence of these sharks is pretty amazing."
On Tuesday state officials expressed pride at the accomplishment of tagging five great white sharks. "The Commonwealth is proud of the efforts of biologist Greg Skomal who works on behalf of the citizens of Massachusetts to further shark research, helping us to understand the behavior of these animals and to act as good stewards of the marine environment," said Energy and Environmental Affairs Secretary Ian Bowles, whose office includes DMF.
In recent years, Mr. Skomal has become a familiar public figure in connection with increasingly frequent news reports of shark sightings along the Massachusetts coast.
Most summers Mr. Skomal provides the scientific counter weight to dramatic accounts that link every shark sighting to a reference to the movie "Jaws."
The shark hype occurs despite the fact that the last known great white shark attack occurred 73 years ago when a great white bit the leg of a 16-year-old boy from Boston while he was swimming in Buzzards Bay off Mattapoisett.
Less publicized is the work Mr. Skomal and his fellow biologists do to understand more about a species that presents a number of questions and is threatened by overfishing in many areas of the world.
Mr. Skomal is the lead author of a study, "Transequatorial migrations by basking sharks in the western Atlantic ocean," published in the June 23 issue of Current Biology that unlocked one of the mysteries associated with basking sharks, the world's second largest fish. The study identified the shark's previously unknown winter habitat.