Cape sharks shallow depths study is ‘very illuminating’: Atlantic White Shark Conservancy researcher
A new shark study that reveals the predators spend nearly half of their time at shallow depths along the Cape is “really powerful” data that helps drive home the message that sharks may prowl near beachgoers, the study’s lead author tells the Herald.
Although the overall risk posed to humans by white sharks is low, there is a “high potential” for overlap between white sharks and recreational water users off the Cape, according to the shark researchers who wrote the groundbreaking study that shines light on white sharks’ habits and movements.
“It was very illuminating and really helpful to have a number to help drive it home to beachgoers who might not think of sharks all the time, and not be as familiar as locals,” said lead author Megan Winton, a research scientist at the Atlantic White Shark Conservancy.
“A lot of people who come to the Cape don’t realize how close to the shore they are,” she added. “Getting a number to quantify the proportion of time is a really powerful way to increase the public’s awareness of their presence.”
Great white sharks are regularly spotted off the Cape during the summer and fall, the peak of tourist season.
But until now, researchers did not know how much time the sharks spent in shallow water close to shore as they hunt for seals.
The scientists from the Atlantic White Shark Conservancy, Arizona State University and the Massachusetts Division of Marine Fisheries examined tagging data to determine how much time sharks spend in shallow water.
Researchers tagged 14 sub-adult and adult white sharks off the Cape in 2017.
“There were more than a million data points to analyze,” Winton said, adding, “These tags archive temperature and depth data every 10 seconds.”
During the sharks’ resident periods along Cape Cod, the sharks spent almost half (47%) of their time at depths of less than 4.5 meters, or about 15 feet. The researchers classified depth records of 0 to 4.5 meters as “shallow” — where swimmers, surfers, boogie boarders and paddleboarders spend their time.
Sharks spent 95% of their tracked times at depths of 0 to 100 feet, and in water temperatures ranging from 48 to 69 degrees.
The results provide the first glimpse into the habitat use of white sharks off the Cape, and Winton hopes the data will improve beachgoers’ awareness of sharks.
“The results help reinforce the current public safety messaging, and suggests water users reduce their risk of having a negative interactions by staying close to shore,” Winton said. “And to follow the ‘shark smart’ behaviors.”
In addition to staying close to the shore, researchers advise people to avoid being in the water at night and during periods of low ambient light levels.
Since 2012, there have been four attacks by white sharks on humans along the Cape — including one fatal attack, the first in Massachusetts since 1936. Arthur Medici, 26, was killed while boogie-boarding at Newcomb Hollow Beach in Wellfleet.
from Boston Herald https://ift.tt/39tTfkw
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