Changing Seas Bring ‘Turtle Stranding Season’ to Cape Cod

ORLEANS, Mass. — The Kemp’s ridley sea turtle, among the rarest and most endangered of the seven species of sea turtles, was found motionless shortly after high tide on Cape Cod’s Skaket Beach. It was in dire straits.

The chilly fall ocean temperatures off Cape Cod had dangerously dropped its body temperature, creating a hypothermia-like condition called cold-stunning. The cold water had slowed the animal’s heart rate, making it lethargic and incapable of swimming back to warmer waters.

Bob Prescott, a former director of the Mass Audubon Wellfleet Bay Wildlife Sanctuary, carefully scooped up the creature, soon to be designated No. 112, to try to save its life.

“We treat them all as if they are alive,” said Mr. Prescott, who is widely credited with raising awareness of the sea turtles’ surprising presence in the Cape. Since Mr. Prescott first found a stranded turtle on a beach in the region in 1974, the numbers have only been rising.

It’s a phenomenon that researchers increasingly link, much like the 11 inches of sea level rise the region has experienced since 1922, to climate change.

Worldwide, the oceans have absorbed more than 90 percent of the heat trapped by human-caused greenhouse gas emissions. The Gulf of Maine, which the Cape curls into, has been warming “quite rapidly,” said Lucas Griffin, a postdoctoral researcher in the department of environmental conservation at the University of Massachusetts Amherst. “Some put it at 99 percent faster than the rest of the ocean.”

The Kemp’s ridley turtles travel from their hatching sites along the Gulf of Mexico following ocean currents. As water farther north warmed, they followed. Most of the turtles that keep turning up on Cape Cod tend to be between 2 and 4 years old.

“It seems that Kemp’s ridleys, and it looks like loggerheads, too, are migrating farther north in the summer as the water temperatures increase,” said David Steen the herpetology research leader at the Florida Fish and Wildlife Conservation Commission. “But then when winter hits, they’re unprepared for that drop in temperature and they get cold-stunned.”

In 2014, a record 1,241 cold-stunned animals arrived, according to the Sanctuary’s data.

“On the Cape now, people actually refer to it as sea turtle stranding season,” said Tony LaCasse, then the media relations director at the New England Aquarium (Mr. LaCasse left the aquarium shortly after this article was reported). The aquarium is a key link in the human chain dedicated to the rescue and rehabilitation of cold-stunned sea turtles.

The chain begins on the beaches of Cape Cod, where volunteers, including families, retirees and a literature class from Penn State, walk the shoreline in search of turtles.

They head out when water temperatures dip into the low 50 degrees Fahrenheit and after a day or two of sustained winds have helped to blow the turtles ashore, conditions which a recent study confirmed are strongly linked with sea turtle stranding. The Mass Audubon Wellfleet Bay Wildlife Sanctuary helps coordinate the efforts.

After 112 was removed from the beach, Mr. Prescott drove it to the sanctuary about 15 minutes away. Turtles brought to the sanctuary are typically placed in a room warmed to 55 degrees Fahrenheit, or about 13 Celsius. The temperature is vital — warming a cold-stunned turtle too quickly can stress the animal, potentially killing it. Managing stress is also why everyone in the turtle room whispers.

“Their cortisol levels, their stress hormones, are very high, so we try to avoid stimulating them further,” said Karen Dourdeville, who coordinates the sanctuary’s program for rescued turtles.

Stress, and practicality, is why after the turtles are weighed, measured and scanned for tags similar to the microchip implants used to track pets, they are placed in a banana box. (So far, three of the turtles rescued this year had been cold stunned and rescued before, one in 2017 and two in 2018.)

“Banana boxes are perfect,” said Jenette Kerr, marketing and communications coordinator at the sanctuary. In addition to being easy to carry, “you can see inside but the turtles can’t see a lot.” The limited view helps keep the turtles calm.

This operation would have been unthinkable 40 years ago, because, back then, it was unclear that there were many sea turtles around Cape Cod. The scant evidence that did exist, such as sea turtle bones among Native American artifacts dating back centuries, or in the work of Henry David Thoreau, who wrote of hearing of a stranded sea turtle “as large as a barrel,” were generally chalked up to solitary incursions.

Mr. Prescott, who retired this summer after 40 years as director of the wildlife sanctuary in Wellfleet, spotted his first cold-stunned sea turtle in the region in 1974. “It was dead,” he said.

The following year he found two.

Other people started to walk the beaches too, after Mr. Prescott wrote about the turtle in the local paper. “By 1978, ‘79, it became pretty obvious that there were turtles here every year,” he said.

“The single variable that helped explain this trend was warmer late-fall temperatures,” said Dr. Griffin, who published a study that looked into what was causing the rise in cold-stunning.

Turtles are cold-blooded and depend on surrounding temperatures to regulate their internal body temperatures, which makes them extremely sensitive to ambient temperatures.

Cape Cod’s shape, a hooked peninsula, is especially confusing to the migrating turtles. As they move south they enter the open portion of the hook, the only way in or out. To leave, turtles would have to swim back out the way they came, north around the hook. It’s so puzzling that turtles aren’t the only animals that get stuck. In January, dolphins often require rescue.

From the Mass Audubon Wellfleet Bay Wildlife Sanctuary, 112 was taken to an animal hospital run by The New England Aquarium just outside of Boston. It’s here where the turtle was given its number — written with a paint marker on its shell. Responsive turtles are placed in a pool of water heated to 55 degrees Fahrenheit and helped to swim to help circulate the blood in their bodies.

Over four days, the turtles are gradually exposed to warmer temperatures, slowly increasing from 55 degrees to 75 degrees.

“And that’s where they’re considered to be at a stable temperature,” said Melissa Joblon, an associate veterinarian at the New England Aquarium.

Every animal is also given fluids and an antibiotic, “but if their lungs look great and they’re doing well, that’s all they might need,” said Dr. Joblon.

But 112, like roughly half of the turtles that end up near the Cape, did not arrive in good condition. Dr. Joblon had to intubate it and put it on a breathing assist machine.

Stable turtles, however, are sent to aquariums across the Atlantic Seaboard, because the hospital was not designed to handle the current volume of turtles. The turtles often travel by private plane, courtesy of a network of volunteer pilots organized by a nonprofit group called Turtles Fly Too. “Shortening the transition time reduces stress on the turtles and improves outcomes,” Mr. LaCasse said.

Cold-stunning is not the only threat facing Kemp’s ridleys. Sex determination in sea turtles depends on temperatures, “so with the shifting climate toward warming temperatures, in theory you could have a turtle population that’s increasingly female and that presents obvious problems over time,” Dr. Steen said.

Rising tides can also affect sea turtle nesting sites, including the Kemp’s ridley nesting sites along the Gulf of Mexico, harming eggs. And, there’s the question of how humans respond to the effects of climate change. If there is a retreat from the ocean’s edge, allowing the dune ecosystem sea turtles need to lay their eggs to persist, there’s hope. But building sea walls to protect buildings near the shore would cut the turtles off from the beach further endangering them.

It’s too soon to tell how 112 will fare. Eleven days after being rescued it was transferred to the National Aquarium in Baltimore, which meant that it was stable enough to travel — a positive sign. It has since been renamed Stilton (this year’s theme for names for the rescued turtles, voted on by volunteers, was cheese). If it is rehabilitated, it will be taken to a beach with suitable ocean temperatures and released back into the wild.