This photo, taken July 31, 2020, via a drone near Bailey Island in Harpswell, shows a great white shark, according to a Massachusetts shark expert. Credit: Courtesy of Maine Marine Patrol

Almost a year after a woman was fatally attacked by a great white shark while swimming in a cove in Harpswell, the state is nearly tripling the number of acoustic shark detectors in the waters along Maine’s coast.

Following the fatal July 27, 2020, attack, the state Department of Marine Resources deployed eight acoustic receivers in coastal waters, spread out between Wells and Popham Beach, after it had already placed three in Saco Bay off Old Orchard Beach. The receivers, 11 in total, recorded pings from sharks that had been tagged with transmitters by researchers who are collecting data about the presence of sharks along the coast.

The shark attack last summer, which killed Julie Dimperio Holowach, 63, of New York City, was only the third fatal shark attack in New England since 1936. There have long been seasonal sightings of large sharks on Maine’s coast, though such sightings are considered uncommon. Holowach’s death remains the first known recorded fatal shark attack in Maine.

The presence of large sharks in New England waters likely has been increasing in recent decades as a variety of conservation measures have been put in place to protect sharks and seals, which are believed to be the preferred food choice for white sharks.

This summer, the state has deployed 32 acoustic receivers along the southern Maine coast, between roughly York and Boothbay Harbor, according to Department of Marine Resources spokesperson Jeff Nichols. 

“Our array focuses predominantly on coastal areas where there’s high beach recreation,” Nichols said Thursday.

To help with the collection of data, the state also has created a shark sighting webpage where people who see large sharks in coastal waters can enter information and upload photos of what they saw.

The receivers do not transmit data remotely, and are not intended to be an active warning system to people who might be visiting nearby beaches when a shark signal is detected. The sensors have to be retrieved, brought to shore and then have their collected data downloaded for researchers to find out when they detected sharks.

Maine state beaches and some other public beachfront areas, including in Harpswell, instead are using shark flags to alert visitors when a shark has been spotted in the area.

Nichols said the state plans to retrieve the sensors later this month, download the data and then put them back in the water where they will remain until late fall.

The purpose of the sensor system is to ensure that officials have data to support their efforts “to protect public safety and to provide important information about migration and habitat use of great white sharks in the Gulf of Maine,” state marine resources officials said.

The collected data is shared with the New England White Shark Research Consortium, which includes fisheries officials in Maine, Massachusetts, New Hampshire, Rhode Island and Canada as well as marine conservation groups and federal and university researchers. After being reviewed by researchers, the data also is shared with the public via Sharktivity, an app developed and run by consortium member Atlantic White Shark Conservancy.

In 2020, when 11 sensors were deployed in coastal Maine waters from late July through late November, they detected 45 tagged fish swimming along the coast. Of those, 16 were sharks — 14 white sharks, one blue shark and one sand tiger shark, according to the Department of Marine Resources.

In all, the sensors recorded more than 20,000 pings from the tagged fish, of which roughly 1,000 came from the tagged sharks.

Nichols said that there have been reports of white shark sightings along Maine’s coast this summer, but none of them have been confirmed. Several of those sightings turned out to be basking sharks which, though large, are filter feeders that pose no threat to people, he said.

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A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....