Shark-detecting buoys put in place off Duxbury, Plymouth coasts

Ida Parker (left) and Kristin Orr, who were attacked by a great white shark last year while kayaking, thanked Plymouth harbormaster Chad Hunter and other rescuers Friday. Craig F. Walker/Globe Staff

The South Shore’s first shark-detecting buoy was set afloat off Duxbury Wednesday, with three more placed along the Plymouth coastline Friday.

The buoys, attached to acoustic receivers, will track any tagged sharks swimming within a 200-yard radius.

“We’re trying to get a sense of local movements of white sharks and their behaviors for the purpose of public safety,” said Gregory Skomal, a senior biologist with the state Division of Marine Fisheries.

The receivers on the buoys detect sounds emitted by the transmitters on tagged sharks, Skomal said. The receivers will record the date and time when the shark swims by, he said, and scientists from the Division of Marine Fisheries will download information from the receiver every couple of weeks.

Tracking buoys have floated off Cape Cod since 2010, monitoring shark movements in Chatham, Orleans, and Truro, Skomal said, and additional receivers have been added each year.

Plymouth harbormaster Chad Hunter said Friday that officials are seeking information about the sharks’ behavior that might help keep residents safe.

“Chatham has been a shark hot spot for years, and as the population of great whites are increasing there, smaller sharks are being pushed to the surrounding areas,” he said. Shark numbers “are now higher than what they used to be, and the sighting off Duxbury and the kayak incident has caused the South Shore to want to know more.”

Last August, officials closed Duxbury Beach after a shark sighting, and one month later, a great white shark attacked two kayakers in Plymouth.

Ida Parker, 29, and Kristin Orr, 32, were paddling their kayaks in Manomet on Sept. 3, watching as seals “popped up” around them before they heard a loud bang, Parker said.

“The shark breached and hit [Kristin’s] kayak. Mine was flipped over,” Parker recalled in a phone interview Friday.

The incidents spurred residents in Plymouth and Duxbury to take action.

The town of Plymouth, the Division of Marine Fisheries, and the Atlantic White Shark Conservancy pooled about $4,000 to pay for acoustic receivers and mooring equipment to make two of the three shark-detecting devices that were put in place Friday.

Joshua M. Bows, 40, a Plymouth native and president of Merrill Corp. – a site-planning, civil engineering, and land surveying firm – donated $1,500 to purchase a third receiver, while the Plymouth 400 Bass and Blue Fishing Tournament Committee, of which Bows is a member, donated $600 for the shark-detecting apparatus’s rigging equipment.

The receivers “show whether this was a fluke event or whether sharks routinely travel the area,” Bows said. “It helps us understand whether we need a shark management program or if it was a random event.”

A shark-detecting buoy was deployed Friday at Manomet Point.Kristin Orr

In Duxbury, Jackson Kent, president of the Bayside Marine Corp. marina, became interested in Skomal’s research. Kent said his business donated $3,000 to pay for the buoy installed in Duxbury Wednesday.

“The more we get to learn, the safer we’re going to be in the water,” he said.

The Duxbury buoy floats 200 yards east of the first crossover, a pathway from the back of Duxbury Beach to the front of the beach, according to Duxbury’s harbormaster, Donald C. Beers, III. Hunter said buoys will be posted in Plymouth at Gurnet Point and Ellisville Harbor State Park, as well as Manomet Point.

Parker and Orr returned to Manomet Point in Plymouth Friday for the deployment of one of the buoys, which they adorned with stickers from the Atlantic White Shark Conservancy, Parker said. After scrawling a message thanking the first responders who helped them last September, the women wrote a thank-you note to the shark “for knowing kayaks are not food.”

“It’s interesting data to see if tagged sharks in Chatham are coming over here,” Parker said. “It’s important to get as much information as we can to help them and us.”

The boom in great white sharks began when the Marine Mammal Protection Act of 1972 triggered a growth in gray seals, the sharks’ meal of choice.

Shark season kicked off on the East Coast this summer with eight attacks off the North Carolina coast. In one of them, a Wareham man, former Boston Herald editor Andrew Costello, was bitten July 1 on Ocracoke Island. An official there said he believed a bull shark was involved in that attack.

In 2012, a shark bit Boston native Chris Myers off Ballston Beach in Truro. It marked the first great white shark attack on a Massachusetts swimmer since 1936, when a Dorchester teen was killed while swimming at Crescent Beach in Mattapoisett.

Sixty-eight sharks were sighted off Cape Cod last year, with 18 of them tagged, Skomal said. Four sharks have been sighted in Massachusetts this year, one of which was tagged.