Heather McCarronCape Cod Times
With the arrival of April, it's safe to say winter is in the rearview mirror, and soon enough Cape Cod's population will swell with returning summer residents and visitors.
So, too, will the surrounding waters swell with another seasonal population — great white sharks.
It's a time of year shark scientists here look forward to.
"We're very much interested in looking for patterns in behavior that will be informative relative to public safety. A lot of focus is on getting a sense of where white sharks are likely to be, when and how do white sharks feed on seals, so that we can share that with public safety officials and the general public," said shark expert Greg Skomal, a senior biologist with the Massachusetts Division of Marine Fisheries, who spends much of his time in the summer studying the Cape's white sharks.
Drones above the Orleans' coast will keep an eye on shark behavior and hunting tactics.
Skomal and fellow researchers are already gearing up for the sharks' summer return — June through November, peaking August through October — and they've got plans to pick up where they left off last season on a pilot program in Orleans, in collaboration with the Chatham-based Atlantic White Shark Conservancy, using drones to record videos of white sharks off Nauset Beach.
Orleans Natural Resources Manager Nathan Sears said this is all part of the ongoing effort to understand the sharks' nearshore behavior and hunting tactics, "and to investigate potential relationships between environmental conditions and predatory behavior."
"This technology will be paired with tracks of tagged sharks through a fine scale acoustic receiver array deployed off Nauset Beach by the Center for Coastal Studies," Sears said.
Working to understand white sharks Tracking Cape Cod's great white sharks: White Shark Conservancy begins 10th year
Drones may help identify some sharks near beaches but cannot be relied upon as an early detection system.
The goal is to evaluate the effectiveness of using drones to identify white sharks under various environmental conditions. While this work is still primarily for research, when sharks are spotted that information will be relayed to Nauset Beach staff to warn beachgoers of their presence.
"It is important to note that the presence of the drone technology does not mean that all sharks in the area will be spotted," Sears said. "This technology has not been proven effective in locating and identifying white sharks on a regular basis based on the challenging conditions associated with the North Atlantic ocean."
He stressed the drone use is a pilot project "and should not be relied on for public safety. Beachgoers should adhere to all shark safety tips and follow instructions of the lifeguards, even when a drone is being flown."
Cape Cod is a white shark hot spot - and the only known 'aggregation site' on the Atlantic coast.
In recent years, Cape Cod has emerged as one of the world's white shark hot spots, and the sharks' only known aggregation site on the Atlantic coast, according to Skomal. Because of this, it's become a premier place for conducting research and testing out new observational, detection and warning technologies.
Last season, according to the conservancy, researchers identified 55 sharks in Cape Cod waters that were not previously observed here. That doesn't necessarily mean there are more sharks. While there are sharks that return year after year, "at the same time we have individuals that don't come back," Skomal said.
"Many of them will just stop by for a few days. So it's really in a state of flux all the time," he said.
Skomal and fellow researchers have observed white sharks in Cape Cod Bay and from Provincetown to the southern tip of Monomoy. The most activity tends to be off the Outer Cape beaches.
Cape Cod is host to lots of seals for sharks to feed on.
White sharks are coming to Cape Cod because it has lots of gray seals, a favored food source.
What's happened over the last five decades is what Skomal calls "a conservation success story" for the seals. Once hunted to the brink of extinction, they have rebounded since the Marine Mammal Protection Act was enacted in 1972. Historically, he noted, "seals were actually pretty prolific and well distributed and abundant throughout the region."
"And now, after 50 years of protection, we're seeing these animals respond to that," Skomal said. "If there's high densities of seals, white sharks are going to be drawn to that."
The sharks and seals are engaged in an ancient and natural predator-prey interaction, Skomal said. What it all comes down to for people is getting a better understanding of the interactions so they can adjust their behavior accordingly.
Scientists have tagged about 300 sharks with acoustics transmitters, to better track them.
Toward that end, scientists work to tag sharks, and have an array of acoustic receivers they deploy each season around Cape Cod to keep tabs on them.
"We've got about 300 white sharks tagged with acoustic transmitters. We use that technology to study their behavior and get a sense of their movements," Skomal said.
He expects to begin working with the conservancy to return the receivers to Cape Cod's waters by early May.
Most of the receivers just log the data and archive it until researchers can collect it, Skomal said. There are also a handful of more advanced "live," or real-time, receivers that can alert beach managers and lifeguards to a shark detection right away. Because they cost about 10 times more than a regular receiver, with a price tag of about $15,000, there are fewer of them.
Last year, five of these were in the water. Sears said he's been told a sixth may be added this summer.
Since there are not many live receivers, Skomal said, "we try to put them off some of the more popular swimming beaches on the Outer Cape — places like Newcomb Hollow, Head of the Meadow, Nauset Beach."
Check out the list of tagged sharks and watch their trek around the Cape.
The conservancy has put acoustic white shark detection data at people's fingertips with its White Shark Log Book, available on its website. It also offers Sharktivity, its shark sighting and resource app. Sightings are fed into the app by researchers, safety officials, and users who upload photos that are verified by the New England Aquarium.
The app integrates detections from real-time receivers, which are represented as yellow icons on the app, Sears said. When a shark is detected, the icon changes to purple; a summary of tagged sharks detected on a given day can be viewed by clicking on the icon.
"These notifications are being provided to raise awareness about the presence of white sharks off the coast and should not be relied on for public safety," Sears said. "It is important to remember that these buoy receivers only detect tagged sharks, which is only a percentage of the population."
The best way to avoid a shark attack is to change human behavior during peak season.
Sears advises beachgoers not to go further than waist deep, always stay inside the surf break, and avoid the edges of sandbars where deep water troughs are likely, since the sharks tend to use them to ambush their prey.
"Distance from shore is not relative," Sears said. "Often deep troughs can run parallel and in close proximity to shore."
Finally, he said, "always have someone on the beach keeping an eye on you while you cool off."
Skomal has similar recommendations, and also advises beachgoers to be aware of their surroundings and to look for seals.
Heather McCarron writes about climate change, environment, energy, science and the natural world, in addition to news and features in Barnstable, Brewster and Falmouth Reach her at hmccarron@capecodonline.com, or follow her on Twitter @HMcCarron_CCT
Get the Cape Cod news that matters delivered to your inbox. Sign up for our newsletters.
