Saving Cold-Stunned Sea Turtles

It was by chance that Karen Dourdeville was visiting the Vineyard when the calls came in about three juvenile green sea turtles, cold-stunned and stranded, washed up on the shore — two in Tisbury Great Pond and one in Katama Bay. It was the day before Thanksgiving, and Karen, the Sea Turtle Stranding Coordinator typically based at Mass Audubon’s Wellfleet Bay Wildlife Sanctuary, wasted no time. She quickly retrieved the turtles, carefully packed them in boxes, labeled them, and boarded the last ferry to Woods Hole. 

“I just sat down on the freight deck with these boxes, each containing a live green turtle,” Karen said in a phone call with Bluedot.

Her swift response is part of a larger, highly coordinated effort to address the number of cold-stunned sea turtles stranded on beaches on Cape Cod, the Vineyard, and Nantucket, as well as on Massachusetts’ north and south shores. Sea turtles are cold-blooded and rely on their external temperatures to regulate their body heat. When air and water temperatures drop, so does their body temperature. The turtles become cold-stunned and are weak and unable to swim.

Three species found in New England are vulnerable to cold-stunning: green sea turtles, loggerheads, and the critically endangered Kemp’s ridley. These turtles are found swimming in New England waters all summer through early fall, and are often found cold-stunned from November through mid January. “None of these turtles can stay here all winter. It’s too cold, so they’re trying to go south,” Karen said. 

While the islands don’t see nearly as many cold-stunned turtles as the beaches on the Cape, seven cold-stunned sea turtles washed ashore on Nantucket this season, at various places along Coatue: four green sea turtles (two alive, two deceased), and three Kemp's ridleys (two alive, one deceased). On the Vineyard, eight washed up this year — three alive and five dead. Two of the turtles were Kemp’s ridleys, which were found washed up in Katama Bay and on the north shore of West Tisbury. The other six were juvenile greens — which are less common in New England. It was also unusual to find them in the Tisbury Great Pond.

The Tisbury Great Pond is brackish for most of the year, but a few times a year, based on water levels, the pond is cut at the south end, letting salt water flush in. The pond was opened August 21, and it closed naturally by September 15.

“Presumably, these greens got in during that window,” Karen said, adding that the pond wasn’t reopened again in the fall as it often is because of the drought, and because there was a virus affecting oysters, which are susceptible to higher salt. “So the decision was made not to reopen it,” Karen said. “So these greens, plus another green that came out of the Great Pond, were thriving and living in there until they got stranded.”

Roughly 25% of the cold-stunned turtles Karen’s team responds to don’t survive, but for the ones that do, their journey back to sea represents the efforts of a network of local, regional, and national conservation organizations working together to save these threatened species.

Healthy oceans need sea turtles. Loggerheads and leatherbacks help control jellyfish populations, while green turtles help maintain healthy seagrass beds by eating and pruning them, increasing their capacity to support biodiversity and carbon storage. Kemp’s ridleys, the smallest and most endangered sea turtles on the planet, play a crucial role in their ecosystems through their unique nesting behavior (large groups of females gather offshore and come onto the beach all at once), making them even more important for scientific study. 

Species specifics

Scientists see the most cold stuns with the Kemp’s ridley. Although Kemp’s ridleys primarily nest in the Gulf of Mexico (which, Karen points out, makes them susceptible to oil spills), some get around the southern tip of Florida and travel up the East Coast. At about the size of a dinner plate, Kemp’s ridleys are the smallest of the three species susceptible to cold-stunning. Green sea turtles are roughly the same size when juvenile  but grow to be three to four feet long and weigh around 300 pounds when they’re adults. They typically come from Florida or Mexico. “But they may go offshore for a while. The ones we get are anywhere from two to seven years old. So they’re kind of swimming and floating in Sargassum weed for a couple years, and then at some point, they head inshore,” Karen said. Loggerheads, which are about three feet long and 250 pounds as adults, “do really quite a circumnavigation of the North Atlantic,” Karen said. Many hatch in Florida, travel to Europe and the Mediterranean, and eventually cross the Atlantic to the Northeast.

As air temperatures rise, it becomes harder for turtles to successfully hatch on southern beaches. “There’s been a huge conservation effort by many people and many organizations to protect nests on vulnerable beaches,” Karen said. 

The majority of Kemp’s ridleys are born along a 30-mile stretch of beach in northeastern Mexico, where conservation efforts by the U.S. and Mexico in the 1980s boosted nesting numbers, “which was wonderful,” Karen said. “And then the Deepwater Horizon oil spill happened in 2010, and numbers plummeted after that. They have risen again, but not as quickly. Are there more Kemp’s ridleys being put in the system? Yes, but we don’t know how many.” 

Karen pointed out that, while nest numbers are an important measure of success, hatching success has become increasingly important. “As the beaches are warming with climate change, the nests can get too hot and not as many eggs hatch. So that’s another parameter people are considering.”

In addition to Kemp’s ridleys, greens, and loggerheads, leatherback turtles also inhabit New England waters from summer to early fall. These giant turtles, measuring six to eight feet long, are not susceptible to cold-stunning due to their size and other physical adaptations. The Wellfleet Bay Wildlife Sanctuary also monitors leatherback turtles, which are more prone to summer strandings. 

“Leatherbacks sometimes are the most common summer stranding,” Karen said. “Many of them get hit by a vessel, which can be fatal, and they wash in.”

Responding to cold stuns

In the past year, Karen’s team responded to around 820 cold-stunned turtles, with the majority found along Cape Cod, where turtles often get trapped in the bay’s “arm” during their migration south. Sea turtles, like many species of fish, are moving further north along the western North Atlantic due to climate change and warming waters stretching as far north as the Gulf of Maine. Not only are our warming water temperatures more hospitable to them, but also, they like to eat here, because our waters are “very nutrient rich,” Karen said. Cold-stunned turtles have been on the rise for over a decade, with a record 1,400 turtles stranded in 2014 and numbers nearly that high in several years since. Though the numbers rise and fall from one year to the next, the general trend upward remains concerning. 

This past season, the eight cold-stunned turtles found on the Vineyard represented more than double the average range of one to four per season. Adam Kennedy, Director of Rescue and Rehabilitation at the New England Aquarium Sea Turtle Hospital in Quincy, said this number might even be a record for the Island. The Aquarium cared for 518 turtles this season, compared to 394 last season, including the three found alive on the Vineyard this year.

All reports about cold-stunned turtles in the region go through Karen’s team at the Wellfleet Bay Wildlife Sanctuary, whose work is conducted under a permit from the U.S. Fish and Wildlife Service (see the box below to learn more about how current government funding could affect sea turtle conservation). When Karen or her staff aren’t already on the islands (which is most of the time) they rely on trained volunteers to respond. On the Vineyard, these volunteers come from the Wampanoag Tribe of Gay Head (Aquinnah) Environmental Laboratory, under the jurisdiction of the Tribe’s Natural Resource Department, and Mass Audubon’s Felix Neck Wildlife Sanctuary. Mass Audubon also trains volunteers on Nantucket, who are members of the Marine Mammal Alliance Nantucket and Nantucket Animal Rescue.

“Sometimes we’ll get calls from the public, or they’ll come through the police departments, but we make sure that we coordinate everything with Karen,” said Andrew Jacobs, Laboratory Manager of the Wampanoag Environmental Laboratory, who has been responding to cold-stunned turtles on the Island for the last 16 years. “When we get to the scene, we’ll take photos before getting a little closer to the animal. We try to minimize stress and look for signs of human interaction, which could be entanglements, or maybe there’s [been] a vessel strike. And then we go a little bit closer. You can usually tell with a cold stun — they look like they’re basically a stone statue. At that point, there are very few signs of life. But sometimes you can see some flippers or eye movements. Basically, they’re shutting down to conserve what little body heat and energy they have left.”

Once a turtle is located on the Island, volunteers package it up — usually in a banana box with some seaweed to help keep it warm — and transport it to the ferry terminal. During the drive, volunteers turn off their car’s heat to keep the turtles at around 55 degrees Fahrenheit, as raising the temperature too quickly could put the body into shock and kill the animal. Volunteers then bring the turtle aboard the ferry’s freight deck. “The crew members on the Steamship know about it,” Karen said, adding that a volunteer from her team is ready on the other side in Woods Hole. “Everyone knows who’s going to be there, and there’s a lot of coordination.” 

“We'll do it as quickly as possible, so that way they can get the turtle to a rehabilitation center,” Andrew said. 

Depending on the time of day and capacity at the rehab facilities, some turtles are taken to Wellfleet Bay Wildlife Sanctuary for overnight care, while others are brought to the New England Aquarium Sea Turtle Hospital or the National Marine Life Center (NMLC) in Buzzards Bay for short- to long-term treatment. With so many turtles to rescue, Karen’s team conducts around two transports per day, and capacity at these centers is often stretched thin.

Cold-stunning is “the same thing as a person getting hypothermia in cold water,” said Beth Sobiloff, Interim Executive Director of the NMLC, which cares for turtles for about one to two weeks before transferring them to another rehab center for secondary care. The first step with a cold-stunned turtle, Beth explained, is to give it an ID number and gradually warm it. “We keep them at 55°F for 24 hours, then up to 64°F for another 24 hours, and after that, they can go up to 75°F, and they pretty much stay at that temperature,” Beth said. 

Treatment center staff give turtles a comprehensive physical exam, including bloodwork analysis. This year, they treated many for pneumonia. The team helps the turtles with their first swims in fresh water, providing hydration and removing any debris such as barnacles that may have accumulated during dormancy. “They’ll kind of gradually stimulate the system, maybe rub their flippers and try to warm them,” Beth said. The turtles then move to warmer saltwater environments, where they swim for longer periods. “We make sure their shells stay moist when they’re not in the water because they can’t be in the water 24/7 right away. They’re closely monitored for the first few days.” In the final stage of the warming process, turtles graduate to the 75 degree zone, where they swim around the clock. The team continues to give them daily checkups and medical treatments until they are well enough to move to secondary rehabilitation facilities, and eventually to go back into the ocean. 

At the NMLC, Beth and her team are looking to provide longer-term care to sea turtles and hope to raise funds to add a tank to the two they currently have. “We tend to get gray seal pups earlier now, so it overlaps with the sea turtle season,” she said. “You can’t have seals and sea turtles in the same tank, so we’re looking to get more tanks and life support. It’s a very expensive proposition, but we have to have space at every level.” The NMLC had 49 sea turtles in their care this season.

Karen’s team and volunteers at Felix Neck and the Wampanoag Environmental Laboratory also respond to leatherback and loggerhead strandings in the summer. Last year, the Vineyard saw five summer strandings. Karen encouraged people to report live turtle sightings through the website seaturtlesightings.org. 

“That’s aimed at boaters to report sightings of sea turtles, and then we vet these sightings,” Karen said. “The goal is to educate boaters that sea turtles are here and to watch ahead of their boat and avoid hitting them, which is usually fatal.” The Wellfleet Bay Wildlife Sanctuary also partners with the Martha’s Vineyard Striped Bass and Bluefish Derby to educate boaters and anglers, especially during peak fishing season from August through October.

What happens to the dead turtles?

When cold-stunned turtles die, staff and volunteers freeze the carcasses and store them at the Woods Hole Oceanographic Institute, where scientists later perform necropsy, or an animal autopsy. “That’s really an important piece of the whole story, because that’s where a lot of sea turtle science happens,” Karen said. “We invite scientists, we collect samples for other researchers — there are a number of research projects that those deceased sea turtles contribute to.” These studies are years in the making and include one looking at heavy metal in sea turtle tissue; another looking at microbiome makeup or the fauna in the gut of the turtles; another examining the level of PFAS in sea turtle tissues; and there’s a developing study about aging and sexing turtles — both important parameters for understanding population dynamics.

“It’s not until they become sexually mature that you know the sex,” Karen said, adding that researchers can, however, identify the sex of dead juvenile turtles during necropsis. They can also get a better idea of how old the turtles were during necropsis by severing the front flipper bone. “The turtles deposit rings of calcium there. You can count the rings to determine age,” Karen said. Otherwise, scientists only know a turtle’s approximate age range based on their size. “You get a range of age from size, but more specifically from dead sea turtles,” Karen said. 

Back to the sea

When the cold-stunned turtles are stable, healthy, and ready for release, they are usually flown or driven down south to be released into warmer waters. Through a partnership between the National Oceanic and Atmospheric Administration (NOAA) and the nonprofit Turtles Fly Too, volunteer pilots fly turtles to their southern destinations, such as Florida, Louisiana, North Carolina, Georgia, or Mexico. Many rehab centers in Florida and North Carolina were impacted by hurricanes and were not operational this year, which increased the burden on the New England Aquarium Sea Turtle Hospital in Quincy. As of late February, the New England Aquarium still had 71 turtles in its care — more than average for this time of year, Adam Kennedy said.

If the New England waters are warm enough, the turtles are released from local beaches, often off West Dennis Beach on the Cape. “It’s a nice, large beach,” Adam Kennedy said, adding that it’s south-facing. “At that point, water in the Nantucket Sound is going to warm up, so we start releasing them there.” They won’t release turtles back into Cape Cod Bay out of concern that they might get stuck again.

“Up to 85 percent of the turtles that remain in our Sea Turtle Hospital are released back into the ocean,” the New England Aquarium website states. People can track the movements of many of these rehabilitated turtles through the Aquarium’s interactive online map. Ten rehabilitated turtles from Cape Cod that were in the Aquarium’s care were recently released off New Smyrna Beach in Florida. Another small group will be sent south in late March or early April, and the next group of healthy turtles will be released in May or June. 

“It’s just really important that we know these turtles are out here, and everyone really does provide that extra hopeful conservation piece that we need to get these turtles back out and released to the wild,” Adam added. “Every turtle that comes in here, that is our ultimate goal to get them back out into the ocean.” 

“When you take any animal out of the chain of existence, there’s going to be repercussions down the line,” Beth from the NMLC said. “That’s just the way it is. You change a whole ecosystem when you change one animal, and that’s why conservation efforts are so important for sea turtles as well as for all creatures.”

What should I do if I see a stranded turtle?

Sea turtles typically don’t come ashore unless they are seriously debilitated. Do not attempt to warm them yourself, as warming too quickly could shock them. Sometimes the best course of action is to bring a turtle up to the shoreline and cover it with some dry seaweed, because if the waves come back in, it could get carried back out to sea and “we might lose the animal,” said Andrew Jacobs at the Wampanoag Environmental Laboratory. He also encourages people to enjoy live sea turtles from afar. “It’s an incredible thing to come across them, but we urge people that when you do see them, just enjoy them from afar. Give them space. Please don’t touch them. Let them be as natural as they possibly can.” 

For sea turtles found stranded on beaches along Cape Cod, the South Shore, and the Islands, call the Wellfleet Bay Wildlife Sanctuary at 508-349-2615, option 2. Visit Mass Audubon’s website to learn more about their sea turtle program. For sea turtles found on beaches from Boston north through New Hampshire, call the New England Aquarium’s Sea Turtle Rescue Hotline at 617-973-5247. Live sea turtle sightings can also be reported online at seaturtlesightings.org or by calling 888-SEA-TURT (888-732-8878). 

People can support sea turtle conservation in New England through donations to Mass Audubon’s Wellfleet Bay Wildlife Sanctuary, the New England Aquarium, the National Marine Life Center, and Turtles Fly Too. 

Sea turtle conservation 

Sea turtles in U.S. waters are a federally protected species under the U.S. Endangered Species Act (ESA), which the U.S. Fish and Wildlife Service and the National Oceanic and Atmospheric Administration share responsibility for implementing.

Last year, federal funds were allocated for the first time for sea turtle rescue and rehabilitation, and Mass Audubon’s Wellfleet Bay Wildlife Sanctuary was among the organizations that benefited from this funding. However, this funding was not approved for the current year. “Any federal money for sea turtle rescue and rehabilitation is probably gone now,” Karen Dourdeville said, noting that most of Mass Audubon’s funding comes from private donors, which “has never been more important than it is now.” 

Both the ESA and the Marine Mammal Protection Act were enacted in the early 1970s to protect endangered species and prevent their extinction. These acts have been the focus of recent congressional oversight hearings. Wildlife advocates fear these hearings could set the stage for weakened protections for biodiversity and could strip species of their protected status. But no matter what, Karen said, “our work will continue.” 

– Video courtesy of the New England Aquarium