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Commercial Fisheries News
Volume 36 Number 2
October 2009
True partnership yields landmark shark data
WOODS HOLE, MA – Ever since the blockbuster movie “Jaws” came out in 1975, reports of shark activity have created media frenzies on Cape Cod. And in early September, the Cape was buzzing with excitement over the confirmed sightings of at least five great whites just off Chatham’s Monomoy Island, which these days is carpeted by an exploding population of grey seals.
Fascination with the lurid prospect of people being chomped in two by the apex predators fueled the news as town officials closed beaches ostensibly to protect swimmers.
But what was not so obvious to many members of the public was the behind-the-scenes workings of a long-running partnership between a commercial fisherman and a state scientist to tag and study the big sharks.
Supported by spotter pilot George Breen and Ezyduzit boat operator Nick Chaprales, veteran tuna fisherman Bill Chaprales of Marstons Mills repeatedly ventured into water as shallow as 6' to heave a specially rigged harpoon at the behemoths. The throws were so expert and the equipment so sophisticated that the great whites barely reacted to the impact.
The five pop-up satellite archival tags (PSATs) now embedded in the sharks will collect and store information about where the animals go. After many months, the preprogrammed tags will break free, rise to the surface, and transmit the data via satellite to Massachusetts Division of Marine Fisheries (DMF) senior biologist Greg Skomal.
Skomal heads the Massachusetts Shark Research Program, which was established in 1990 to study the ecology, distribution, and relative abundance of sharks found in the waters of the commonwealth.
The goal of this and other shark tagging efforts is to add to the very limited body of knowledge about these fish.
Basking shark findings
This was only the most recent collaboration between Chaprales and Skomal. Late in June, the scientific journal Current Biology published a landmark paper by Skomal and several colleagues that totally redefined previous thinking on the migratory habits of basking sharks.
Once thought to be a strictly cool-water species, data collected by the PSATs attached by Chaprales over several years revealed that basking sharks migrate to tropical waters in the winter, swimming from the coast of New England to the Bahamas, the Caribbean, and even as far south as Brazil.
The tag data further showed that the enormous gaped-mouthed sharks swim at depths of 600' to 3,000' for weeks, even months at a time.
“Anyone who knows New England fisheries is going to be surprised by these results,” Skomal said. “We thought maybe basking sharks went as far south as Florida.”
The research is important because, like many other highly migratory marine species, the US has taken the lead on conservation only to see other nations allow unmitigated fishing.
“With this new information, we now know that any efforts to conserve this species need to be coordinated on an oceanic and maybe global scale,” Skomal said.
Modified harpoon
Both Skomal and Chaprales have been working with tags since 1995 when they began tagging bluefin tuna with DMF biologist Brad Chase. Molly Lutcavage, then with the New England Aquarium and more recently head of the Large Pelagics Research Center at the University of New Hampshire, joined the effort in 1996, Chaprales recalled.
“We designed a rig to apply the transmitter tag via harpoon. We published the design as the ‘modified harpoon technique,’” he said. “The beauty of it is that you’re not stressing the fish, so you don’t modify its behavior.”
Eli Lott, a long-time crewman for Chaprales, confirmed the observation.
“Seeing those sharks afterwards shows that the tagging doesn’t affect them,” he said.
Chaprales explained that the modified harpoon starts off with a standard harpoon pole.
“We use a small shank that’s able to bend easily so it doesn’t damage the fish, and we put a shock absorber on the end,” he said.
The basking shark project required a few additional refinements.
“We also modified the pole because Greg wanted to place the tags in the same spot each time – at the base of the right dorsal fin,” Chaprales said.
Added Skomal, “We wanted the tag to go to the base of the fin to lock it in and because there are not a lot of nerves or blood vessels there.”
Basking shark project
The basking shark project got its start in 2000 when Skomal was able to get a small amount of funding to purchase one of the very expensive PSATs.
“We figured if we could find a shark, tag it, and get data back, it would give us leverage to get more grant funds,” he said.
To make the case for supporting the project, Skomal argued that tracking basking sharks could help solve a North Atlantic right whale mystery.
He explained that about one-third to one-half of the right whale population disappears each year during the winter. So do basking sharks. Since the two animals eat the same thing – plankton – it stood to reason that figuring out where the sharks go could tell scientists where the whales go.
That convinced the Massachusetts Environmental Trust, which raises money in part from sales of the right whale license plate, to provide some funding. The project then expanded into a collaboration in 2004 with the University of New England, which had a handful of PSATs and NASA funds to study remote sensing technology.
The first two tags placed in late September 2004 popped up on June 15, 2005. The first fish was in northern Florida, which came as no surprise. But the second pop-up just two hours later came off a shark that was between Haiti and Cuba.
“That really got us excited,” said Skomal.
Tagging
Tagging began in earnest in early July 2005 as the Ezyduzit crew, working with Breen and Skomal, placed tags on basking sharks right off the beach in Chatham. The work continued in 2006 and 2007 for a total of 25 tags. Pilots Wayne Davis and Tim Voorheis also helped with spotting and photography.
When it comes to deciding when to shift from fishing to tagging, Chaprales calls the shots for the most part.
“We’re fishing anyway for bluefin tuna. This is what we do for a living. George (Breen) is up looking and we let Greg know when we find sharks,” he said. “I make a decision based on weather and where George says the fish are. We want to be as sure as possible that it’s going to work.”
When conditions are right, Skomal comes aboard. His job at that point is to get the tags ready, program them, make sure they work, record the data, including where the sharks were located, the number of sharks, and their maturity.
The system has worked much better than traditional scheduled chartering of a fishing vessel platform, Skomal said.
“You charter a boat for three days in August, then the weather’s not right and there are no sharks. No way,” he said. “It’s a dynamic scene. Most of the time, it’s Bill’s decision when to tag.”
Great team
This truly cooperative effort, relying on the skills of seasoned commercial fishermen working in concert with respected scientists, is the reason the findings paper, titled “Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean,” drew so much attention in the marine science world.
Referring to the special relationship the team has, Skomal said, “That’s why a lot of people have not succeeded in doing this kind of work. It takes the right partnership.”
A basking shark isn’t an easy shark to catch because it eats plankton, not bait, and because of its huge size, he continued.
“And you don’t want to put me in the pulpit with a harpoon to put that tag on,” Skomal said. “If you do, I’m going to hit the shark in the face.”
Added Breen, “If it weren’t for this harpoon technique, people would have to go underwater to put these tags on the sharks. We’d need some Navy Seals for that job.”
Even still, the work has its risks and surprises.
“It’s dangerous, too,” said Lott. “We had one time when the shark’s tail hit the harpoon.”
Work continues
The data collected to date as part of the basking shark tagging project is so interesting that the National Science Foundation has provided additional funding for the project, enough to purchase 40 more tags.
For Chaprales, tagging a shark provides the same rush as harpooning a bluefin.
“A few weeks ago, I stuck seven in one day doing this. It was just as exciting,” he said.
Chaprales concluded that his goal in working for the project is to have the best possible success for Skomal.
“I know how important it is to Greg and the scientists who put in a lot of work to do this study,” he said. “We’re ready anytime. We’re on standby.”
Lorelei Stevens
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