Three were loggerheads and one was a leatherback. All four turtles washed ashore with broken flippers and severe lacerations, according to a story in the Boston Globe.
Robert Prescott, director of the Massachusetts Audubon Society's Wellfleet Bay Wildlife Sanctuary, said the turtles appeared to have been healthy before being struck.
Loggerheads can weigh 300 pounds but leatherbacks, which feed primarily on jellyfish, are the world's largest sea turtle and can weigh 1,200 pounds. All sea turtles are vulnerable to boat strikes.
The Globe reports that this news comes only days after jellyfish had stung as many as 150 beachgoers off New Hampshire.
Prescott said sea turtles play a vital role in maintaining a healthy marine ecosystem, adding: "With every dead leatherback, we're depleting jellyfish-eaters throughout the world's oceans."
-- Pete Thomas
Photo of healthy leatherback sea turtle release courtesy of Connie Merigo / New England Aquarium