A scientist who has been gaining local knowledge about great white sharks along the East Coast of the U.S. and Canada believes there could be up to nearly 1,000 of them in the Passamaquoddy Bay region during a season and that they may be courting and mating in the bay. While other scientists say that the number of great white sharks in the region cannot yet be estimated, nor can it be determined if their numbers are increasing or if they are mating, they agree that the number of sharks being detected in the bay is growing.
Over the past three years, Steve Crawford, a fish ecologist at the University of Guelph in Ontario, has completed 122 interviews with local knowledge holders about great white sharks, as part of a five-year study. Crawford, who has been researching white sharks all around the northwest Atlantic coastline, believes that Passamaquoddy Bay has the greatest aggregation of large, breeding sharks in the 18- to 20-foot range of any place along the East Coast. He has so far spoken with about a half a dozen people who have seen sharks that size in the Passamaquoddy region, and he noted he has not yet interviewed people on Grand Manan. He said that, based on the interviews he has conducted, there is no place in the northwest Atlantic that has as many breeding-size adults.
To support the hypothesis that great white sharks are mating in Passamaquoddy Bay, Crawford points to two lines of evidence: the occurrence of large breeding-size adults in the area and their behavior. Those behaviors may include: a stationary position, in which a shark holds one position, possibly as a low-level display to other sharks to stay away; tail-slapping, which is a social behavior that could be for both territorial and courtship purposes; breaching, in which a three- to four-ton fish completely exits the water and makes “a huge splash,” which may be a territorial display; charging behavior, in which a shark aggressively goes toward a boat; and following behavior, in which a shark shows a high level of interest and male territoriality. Of these behaviors, the stationary, charging and following behaviors have been reported in the Passamaquoddy Bay area, and Crawford is following up on a lead about breaching behavior having been witnessed.
The charging behavior was seen a few years ago by a Lubec fisherman, James Robbins, who was going by Rodger’s Island in his skiff when he saw the dorsal and tail fins of a large shark. The shark “turned on a dime,” Crawford said and chased the skiff. Robbins turned the boat around, and the shark kept chasing him, which Crawford said “is atypical for sharks.” The encounter in 2020 that Kingsley Pendleton and his family of Deer Island had off St. Andrews with a shark estimated to be 20 feet long — one of the largest ever documented — was similar to charging behavior, with the shark demonstrating a high level of interest in their boat. Following behavior was shown by a shark that followed a canoe being paddled by Pat Barker and her husband near Deer Island back in 2018.
“We should leave them alone, if they are setting up territories,” Crawford said, “and not have people putting themselves at risk.” He said people who are on or near the water need to keep an open eye out for sharks, although he noted they are not “man eaters” and rarely engage with people. The Maine Department of Marine Resources also advises that, while the relative risk of a shark attack is very small, the risks should be minimized.
Crawford pointed out that he is not the only scientist who has put forward the suggestion about white sharks courting and mating in the area. In 1998, a journal article by Paul Mollomo in the Northeastern Naturalist hypothesized that there were more great whites in the waters off Maine and Atlantic Canada than people thought. And Mollomo mentioned a female great white shark found dead on a beach near Deer Island that had numerous nipping lacerations that it may have received when it was impregnated by a male. The article mentioned numerous other shark encounters, including a reported 37-foot shark found in a herring weir on White Head Island in June 1930, which would be the largest white shark ever reported.
Crawford noted that approximately 500 white sharks have been tagged and can thus be detected. Other scientists have estimated that there are at least 10,000, perhaps tens of thousands, of white sharks in the northwest Atlantic. Last year, 45 great white sharks were detected in Passamaquoddy Bay. If only 5 percent, or fewer, of the sharks are tagged, then Crawford calculates that the number that may have come into the bay in 2023 could be approximately 900.
To learn more about the presence and behavior of the large sharks in the area, Crawford is supporting an initiative for individuals or groups to deploy drones over the water. “We may see some interesting behavior,” he noted. Several people in the area have indicated they would be willing to help to deploy drones, and anyone who is interested can contact Crawford. They can reach him at [email protected]. The Maine Department of Marine Resources also is collecting data on sharks, which will be shared with the Atlantic White Shark Conservancy to be uploaded to their Sharktivity app. The app provides users with a recap of shark activity detected by acoustic receivers, in addition to shark sightings. Information and app downloads can be found at atlanticwhiteshark.org/sharktivity-app.
Monitoring data for tagged sharks
While data from shark tagging give some indication about the number of great white sharks in the region, much is still unknown. According to Marc Trudel of the Department of Fisheries and Oceans’ St. Andrews Biological Station, acoustic receivers have been deployed by the station in the Bay of Fundy since 2018 and in Cobscook Bay since 2019. The number and locations, though, have not been consistent over the years. In 2018, there were only 29 receivers, while this year 247 were deployed in the Bay of Fundy, Passamaquoddy Bay and Cobscook Bay.
From the acoustic data, Trudel and other scientists summarize that white sharks are present almost on a daily basis in the Bay of Fundy from late May to late November, with the number peaking in August. On any given day, up to 10 white sharks have been detected, and they have measured on average three meters, or about 10 feet, in length. They are frequently detected in the Quoddy region and have occasionally been detected in the St. Croix River. Some hotspots include Head Harbour Passage between Campobello and Deer Island and the entrance of Cobscook Bay, between Estes Head in Eastport and Comstock Point in Lubec.
The number of white sharks detected in the Bay of Fundy increased from two in 2018 to 89 in 2023, with the total number of unique white sharks detected in the Bay of Fundy during the past six years being 137.
Whether their abundance has increased cannot be answered, Trudel said, since the deployment of receivers has varied over the years and the number of tagged white sharks has increased from 2010 to today. Crawford noted that part of the reason the number of detections has increased is because the number of receivers has also increased. Trudel also said it’s not possible to extrapolate on how many white sharks are in the bay based on the number of detections, because scientists do not know the proportion of sharks that are tagged versus untagged. But he said that “Chances are that the numbers of white sharks are higher than what we detected.”
As for whether courtship and mating may be occurring in the bay, Trudel said that can’t be answered from the data collected so far. He noted that most of the animals that are detected are immature. “For those ones, unless they became sexually mature after they were tagged, it is highly unlikely that they would be courting,” he said.
Other scientists have previously stated that they doubt that great white sharks are mating in the Passamaquoddy Bay area. Two years ago, Heather Bowlby, research lead at DFO’s Canadian Atlantic Shark Research Laboratory, said the number of detections in Passamaquoddy Bay is consistent with research that suggests approximately 20 percent of the wider population in the northwest Atlantic is expected to move northward in any given year. She also stated that nothing in the acoustic or satellite tag monitoring data supports Crawford’s hypothesis about mating and that juvenile white sharks are nearly five times more likely to come to Canada than adults. “The behaviour exhibited by white sharks along the Canadian coastline is consistent with searching and foraging behaviour rather than aggregation behaviour associated with mating,” she said.
However, Crawford pointed out that no tags have yet been placed on the large breeders that are 16 feet and longer, so of course they are not being detected. “That’s why Passamaquoddy Bay is such an extremely important region. It’s not just courtship and mating behaviors but also the opportunity for tagging in this area.”
Greg Skomal, a senior fisheries biologist at the Massachusetts Division of Marine Fisheries, who has studied sharks for more than three decades, also stated two years ago that there is no way to extrapolate the number of tagged sharks picked up by the acoustic receivers to the total number of sharks in the bay. He agreed with Bowlby that there was no evidence of courtship and mating in Passamaquoddy Bay, and he said that the estimate of hundreds of sharks in the bay was unrealistic. Skomal, though, did add, “With the growing abundance of seals over the last two decades, it is reasonable to conclude that more white sharks are likely to be moving into the Gulf of Maine to take advantage of this resource.” And then in a July 2024 episode of Shark Week on the Discovery Channel titled “Great White North” he stated that there is “a very high probability” that the northwest Atlantic white shark population is currently in the tens of thousands, which Crawford said could mean, based on the number that are tagged and the number of detections, that there are several hundred in Passamaquoddy Bay during a season.
In response to the comments from other researchers, Crawford believes it’s unfortunate that some scientists don’t agree with using local knowledge as evidence to support a hypothesis. “Scientists are only on the water for specific periods of time,” he pointed out. He wants people to know that “local knowledge plays a vital role in figuring out what the changes are in breeders in Passamaquoddy Bay.”
