BIDDEFORD — Four months after finding themselves stuck in icy water off Cape Cod, five loggerhead sea turtles that spent the winter in Biddeford are headed south for a second lease on life.

The five turtles, rehabilitated at the University of New England’s Marine Animal Rehabilitation Center, are part of a Sea Turtle Trek that will bring 46 loggerhead sea turtles to Jacksonville, Fla., to be released back into the Atlantic. Those turtles are among the 100 endangered loggerheads that were stunned by cold water and stranded on Cape Cod, shattering previous records and leaving experts searching for the reason.

“This year we were off the charts in terms of the number of sea turtles coming in,” said Tony LaCasse, spokesman for the New England Aquarium in Boston.

Marine biologists have “no idea” why there was an increase in strandings late last year, but some speculate there could be a connection to the warm temperatures recorded in the winter of 2011-12, LaCasse said.

During stranding season — a roughly six-week period in November and December — the New England Aquarium took in 242 sea turtles, including 100 loggerheads. In a normal year, the aquarium gets about 70 sea turtles, including five loggerheads. The influx of loggerheads, all weighing 30 to 100 pounds, created an immediate need for more space to treat them for hypothermia. A network of rehabilitation facilities, including the marine center at UNE, cared for the turtles when the New England Aquarium’s Animal Care Center in Quincy ran out of space.

“It’s a little bit like if you all of a sudden were having giants admitted to a hospital,” LaCasse said.

Stranding season occurs when juvenile turtles ride the Gulf Stream to Cape Cod in late June and July to feed on crabs. If they fail to leave when the water temperature starts to drop in September, inexperienced turtles often find themselves swept into Cape Cod Bay as they try to migrate south. As the water temperature continues to drop, the turtles are increasingly lethargic and don’t move around much, LaCasse said.

Suffering from extreme hypothermia, the turtles wash up on the shores of Cape Cod. Volunteers from the Massachusetts Audubon Sanctuary search beaches around the clock for stranded turtles that then are taken to the New England Aquarium and other marine rehabilitation facilities.

The Marine Animal Rehabilitation Center took in 14 stranded turtles since December. One died and five remain at the center, while the others were taken to Florida to be released, said Kristen Patchett, the center’s rehabilitation coordinator.

The five remaining turtles at UNE — named Jawbreaker, 100 Grand, Gobstopper, Pop Rock and Abba-Zabba — arrived at the Biddeford marine center in mid-December. All weighed between 34 and 91 pounds when they arrived. Asheley Simpson, an animal care laboratory technician at the marine center, said the turtles probably are 5 to 6 years old and could grow to be 250 pounds.

“They have a lot of growing to do still,” she said.

On Wednesday, Simpson helped weigh, measure and tag the turtles in preparation for their trip south. One of the tags is similar to microchips used for dogs and allows researchers to access the turtle’s history from a database.

Working with the loggerhead turtles was rewarding because it helps the species grow its population, but it is “bittersweet” to see them go, Simpson said.

“We just need to get them back out in the wild,” she said. “Hopefully they’ll live long, healthy lives.”