CHATHAM — Like the summer visitors strolling Main Streets on the weekends, a few white sharks have returned to local waters for the season. But like their human counterparts, shark visitors won’t be back in large numbers until the weather warms up a bit more.
The fifth and final season of the white shark population study is underway, and acoustic receiver buoys recorded the presence of three tagged sharks off the Lower and Outer Cape. On June 7, white shark Omar pinged a buoy about two miles south of the Nauset Beach parking lot, and two days later Turbo was recorded passing close to a buoy off Marconi Beach in Wellfleet. Omar was recorded again on June 12 off Chatham’s North Inlet, one day after white shark Sandy was recorded off Chatham. The research is conducted by the Massachusetts Division of Marine Fisheries and funded by the Atlantic White Shark Conservancy.
It’s not the first evidence of white sharks in the area this season, state shark biologist Dr. Greg Skomal said. Nantucketers reported sighting a severely bitten seal in mid- to late-May, and the injury was most likely the result of a white shark predation, he said.
“Our earliest detections are generally late May, but we always couch that with, not all sharks are tagged,” he said.
Still, when researchers went out on a tagging trip last Thursday, they saw no evidence of white sharks.
“The water’s still cold,” Skomal said. While the water temperature off Wellfleet has reached 54 degrees, a slug of cold water remains off Monomoy Island and Chatham, where temperatures are as cold as 48 degrees.
“These sharks don’t like to spend any time in water that cold,” he said. It is possible that the sharks are visiting or transiting the area, “but they’re certainly not staying around in it.”
It is possible that the white sharks are scoping out warmer pockets of water offshore or elsewhere. Because the receiver buoys are located close to the coastline, they don’t show shark activity offshore.
But one incentive for white sharks is already in place: a big food source. Skomal said researchers observed large numbers of seals hauled out on Monomoy Island. When water temperatures rise, white sharks will be there to take advantage of that opportunity, he said. But for now, white sharks are “trickling in, and quite possibly trickling through,” Skomal said.
The Conservancy has updated its “Sharktivity” smartphone app with the locations of the recent acoustic detections and is encouraging mariners, beachgoers and shark enthusiasts to use the app to monitor activity and to report their own sightings.
The group is still raising funds to cover the cost of the final year of the population study, which was the first of its kind in the region. The research resulted in the identification of more than 320 individual white sharks, and will help investigators estimate how many white sharks are likely to be in local waters at particular times of the year.
This summer, tagging trips will take place every Monday and Thursday, weather permitting. This Monday’s trip was scrubbed because of gusty southwest winds, but researchers hope to get out later in the week.
While the five-year population study will come to a close after the 2018 season, there is already a plan for future research, Skomal said. In the future, scientists will focus on sharks' fine-scale movements in a bid to learn more about behavior like feeding and reproduction. Researchers hope to make use of new tags equipped with accelerometers that show shark movements in detail. The research could include an examination of the movements of seal populations, which researchers hope will help them better understand white shark hunting patterns, including how often they feed.
The increase in the number of sharks means increased opportunities for interactions with boaters and swimmers, but Skomal said there’s better public education in place now than ever before.
“I think the towns have done a really good job, as well as the [Cape Cod] National Seashore, of getting the word out that sharks are here,” he said. A working group of beach managers, public safety leaders and researchers have installed informational kiosks at major beaches, and talk about ways to avoid run-ins with sharks. But public education is an ongoing task.
“You’re always going to have people arriving who are unaware of it,” Skomal said. “You’re never done educating.”
Email Alan Pollock at alan @capecodchronicle.com