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Researchers hope to tag 20 sharks off Cape Cod

To gather data on feeding, breeding

FALMOUTH — A team of researchers embarked Tuesday on a monthlong expedition to capture and tag as many as 20 great white sharks in what is expected to be the largest study of the sharks in US history.

Scientists from the Massachusetts Division of Marine Fisheries and the Woods Hole Oceanographic Institution hope to collect a slew of new data on the sharks’ feeding, breeding, and migration patterns, researchers said.

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The number of great whites off Cape Cod has exploded in the past 10 years as the seal population has grown, said Dr. Greg Skomal, a senior scientist with the Division of Marine Fisheries who is working on the expedition.

Not much is known about the great white population in the Atlantic, compared with shark populations in the Pacific and Indian Oceans, he said.

The state began electronically tagging sharks in 2009, and the new push is an effort to rapidly expand the numbers, Skomal said.

“We are playing catch-up, and this is a huge part of that,” he said. “I see this as a golden opportunity to build on the foundation that we have created over the last four summers.”

The researchers’ boat will park in the waters off Chatham, an area teeming with 15,000 seals, a favorite meal for the sharks, said Chris Fischer, the expedition leader and the founding chairman of OCEARCH, a nonprofit that specializes in shark research.

“We are basically basking in the 15,000 seals that are defecating and urinating and bleeding and breeding and stinking,” he said. “We are taking advantage of that opportunity. The white sharks are already predictably there, because that is there, and we are going to get inside of that and become a part of that.”

The researchers will corral the sharks in the water and then hoist them aboard their 126-foot ship using a custom 75,000-pound shark lift, said Fischer. His team at OCEARCH has tagged 65 white sharks around the world since 2007.

Last year OCEARCH tagged two great white sharks with three electronic tags each as a sort of test run, he said. This year the team will attach five tags to individual sharks, collect tissue samples, and perform ultrasounds on the sharks. Tagging each captured shark will take about 15 minutes, said Dr. Simon Thorrold, a senior scientist with the Woods Hole Oceanographic Institute.

“These sharks are going to get a real NASCAR pit stop workover for those 15 minutes,” he said. “What we are going to learn is really incredible in terms of the very detailed information of these individual sharks.”

The tags record the sharks’ location when they come near the surface, as well as the depth of their dives and the temperature of the water they are in.

The data will shed light on where the sharks travel, eat, and mate, Thorrold said.

Fischer said the team will be out until Aug. 29 or until they tag 20 sharks.

Javier Panzar can be reached at javier.panzar@globe.com Follow him on Twitter @jpanzar.
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