Study in Saco Bay aims to fill data gaps about juvenile white sharks

A University of Massachusetts Dartmouth biology professor is leading a first-of-its-kind study to better understand why juvenile white sharks are appearing in growing numbers along Maine's southern coast, working out of Saco Bay as recent shark sightings near a popular Scarborough beach have drawn public attention.

Diego Bernal, who is heading the project, said the central question driving his research is straightforward: whether the sharks visiting Maine's waters represent a one-time occurrence, or whether they are beginning to establish a more permanent presence.

"They're not just passing through," Bernal said of the pattern researchers have begun to document. "We want to understand what that means for the ecosystem and for the people who use these waters."

The study is based primarily out of Old Orchard Beach and Scarborough, areas that have seen increased shark activity in recent summers. This week, social media speculation suggested that Bernal's team was chumming the water — dispersing fish parts to lure sharks closer to shore. Bernal firmly rejected that characterization.

"We don't attract them," he said. "We don't chum. We're really not doing anything that's abnormal."

Instead, the researchers are fishing with baited hooks, a method he compared to striped bass angling, though scaled up. Lines are cast roughly 300 yards offshore, baited with chunks of bluefin tuna or similarly oily fish, and left to wait.

The project holds a special research license from the state, according to Jeff Nichols, a spokesperson for the Maine Department of Marine Resources. Under the terms of that permit, the team is required to notify both the Maine Marine Patrol and local municipalities before each outing, and to adhere to specific operational conditions designed to minimize any risk to beachgoers.

All fieldwork takes place between sundown and sunrise, and never on weekends — the hours when the fewest people are in the water. If swimmers or surfers do appear during a research session, Bernal said, the crew stops work immediately.

"Our first concern is public safety," he said.

When a shark is caught, the team works quickly. The animal is brought into shallow water, measured, sexed, and photographed to document its unique markings. A biological sample is collected, and a tag is attached to the back of its dorsal fin. Bernal said the entire process, from capture to release, takes under two minutes.

"We do not want to harm the animals, so we don't do anything that delays their release," he said. "We work really fast."

So far this summer, the team has made four overnight trips since mid-July. Three came up empty. On Tuesday, however, they successfully tagged two juvenile white sharks.

The broader goal, Bernal said, is to tag 30 juveniles in the area over the course of the study, in hopes of answering a handful of basic but important questions: where do these sharks go, how long do they stay, and do they return the following year?

His approach is deliberately different from existing tagging efforts, which have largely operated from boats in deeper water. By working from the beach, Bernal said, he hopes to reach the sharks that are spending time closest to shore — animals that may behave differently from the adults that other researchers have historically focused on.

"We're not trying to duplicate what's already being done," he said. "We're trying to fill in a piece of the picture that hasn't been filled in yet."

Maine has become an increasingly active site for white shark research in recent years. According to an annual report from the Maine Department of Marine Resources, the state deployed 36 passive acoustic receiver sites along its coastline in 2025, stretching from Ogunquit Beach to the Canadian border. During the 2025 season, those receivers detected 19 individual white sharks across 95 days, bringing the cumulative total of unique sharks identified in Maine waters since monitoring began in 2020 to 105.

Approximately 300 white sharks now carry acoustic tags, most of them affixed by researchers from the Massachusetts Division of Marine Fisheries, the Atlantic White Shark Conservancy, and the National Oceanic and Atmospheric Administration. Only four have been tagged in Maine. Notably, in both 2024 and 2025, the sharks recorded most frequently in state waters were among those originally tagged locally — a pattern the state report described as potentially significant.

"This trend may indicate a potential difference in residency patterns between white sharks tagged elsewhere and smaller juveniles tagged locally," the report noted, "though further research is required to confirm."

For Bernal, that open question is exactly what makes the work worth doing. His team has prepared informational pamphlets to distribute to curious beachgoers and stands ready to explain their methods to anyone who asks.

As sightings continue at Pine Point Beach and elsewhere along the Saco Bay shoreline, Bernal said he hopes his study can help replace speculation with something more durable: reliable data about what these animals are doing, and why.

"We're at the beginning of understanding this," he said. "There's a lot we don't know yet — but we're going to find out."