Expert insights from Alyssa Fessett, senior sea turtle biologist, The Florida Aquarium
Sea turtle cold-stunning is a hypothermic state that can occur after prolonged exposure to cold water, often when temperatures fall to around 50 F or below. Affected turtles may become weak, lethargic and unable to swim, leaving them at risk of drifting with currents or washing ashore.
These events are especially common during late fall and winter, when sudden temperature drops and coastal geography can trap sea turtles in rapidly cooling bays and nearshore waters. Large numbers of turtles can become cold-stunned at once, creating widespread stranding events that require a coordinated response. Conservation organizations, scientists and volunteers work around the clock to rescue stranded turtles, provide rehabilitation and return them to the wild, giving cold-stunned turtles a second chance.
Key takeaways
- Cold-stunning can occur when sea turtles are exposed to water temperatures around 50 F or below for an extended period.
- The unique, hook-shaped geography of Cape Cod, Massachusetts, frequently traps migrating sea turtles trying to head south for the winter.
- Cold-stunned turtles can go weeks or months without food, and their core body temperatures may drop up to 20 F below normal levels.
- Saving stranded sea turtles relies on collaboration between beach monitors, veterinary teams and volunteer transport networks.
- The frequency of cold-stunning events has increased over the past decade, driven in part by rapidly shifting ocean temperatures in the Gulf of Maine.
Are sea turtles cold-blooded?
Yes. Sea turtles are ectothermic, or cold-blooded, which means they can’t produce their own body heat the way mammals and birds do. Instead, their body temperature rises and falls with the water around them.
Why do sea turtles become cold-stunned?
Sea turtles become cold-stunned because they’re cold-blooded — they can’t regulate their own body temperature and depend on the surrounding water for warmth. So, when that water turns cold and stays cold, their metabolism slows dramatically, a hypothermic state that makes it difficult to swim, dive, feed or escape predators.
“When sea turtles are out in the wild, if the water temperatures drop too far, their bodies can’t keep up with that, so they become lethargic and really susceptible to secondary types of medical complications,” said Alyssa Fessett, senior sea turtle biologist at the Florida Aquarium.
Where does cold-stunning occur?
Sea turtle cold-stunning can happen wherever water temperatures drop rapidly and turtles can’t reach warmer water in time. Shallow bays, estuaries and enclosed coastal areas are especially dangerous, because the local geography can trap turtles as they try to migrate offshore.
Cold-stunning events have been documented in several regions:
- Cape Cod Bay, Massachusetts: Cape Cod experiences the most frequent large-scale sea turtle cold-stunning events in the United States. Its hook-shaped coastline can trap juvenile turtles as they migrate south, leaving them vulnerable when water temperatures rapidly decline.
- Long Island Sound and the mid-Atlantic: Prolonged periods of cold weather can affect turtles remaining in shallow bays and coastal waters before they reach warmer offshore habitats.
- Gulf of Mexico: Severe winter cold fronts have caused cold-stunning events in shallow coastal habitats, particularly among green sea turtles.
The species affected can vary by region. Kemp’s ridley sea turtles are rescued most frequently during Cape Cod cold-stunning events, although loggerhead and green sea turtles are also affected.
What are the signs of a cold-stunned sea turtle?
A cold-stunned sea turtle shows recognizable signs, most tied to slowed body function and weakness.
| Sign | What It Means |
|---|---|
| Lethargy or no movement | The turtle’s metabolism has slowed significantly, leaving it weak and unable to respond normally. |
| Floating at the surface | Cold-stunned turtles often cannot dive or swim effectively because their muscles no longer function properly. |
| Washed ashore on a beach | As they lose strength, turtles may drift with currents and waves until they become stranded. |
| Cold body temperature | The turtle’s body temperature drops with the surrounding water, causing its bodily functions to slow. |
| Slow or shallow breathing | Cold-stunning reduces heart rate and respiration, making the turtle appear lifeless even though it may still be alive. |
| Inability to swim or right itself | A cold-stunned turtle often cannot flip over, escape predators or return to deeper water without assistance. |
| Visible injuries or algae growth | Some turtles develop wounds, infections or algae buildup after remaining weak and inactive in cold water for extended periods. |
What to do if you find a cold-stunned sea turtle
A cold-stunned sea turtle may look motionless — even lifeless — but it could still be alive and in urgent need of professional care. The safest way to help is to avoid intervening directly and contact trained wildlife responders as soon as possible.
- Don’t return the turtle to the water. A cold-stunned turtle may be unable to swim or regulate its body temperature and could drown if placed back in the ocean.
- Don’t attempt to warm the turtle yourself. Rapid temperature changes can place additional stress on the animal. Wildlife rehabilitators gradually raise its body temperature under veterinary supervision.
- Report the stranded turtle immediately. Contact your state’s marine wildlife rescue organization, NOAA Fisheries or local authorities so trained responders can assess and transport the animal.
- Keep your distance while waiting for help. Avoid touching or moving the turtle unless instructed by wildlife officials and keep pets and bystanders away to reduce stress.
Following these steps gives trained responders the best opportunity to stabilize the turtle and begin any necessary rehabilitation.
How are cold-stunned sea turtles rescued?
On Cape Cod, cold-stunned sea turtles move through a coordinated rescue and rehabilitation network. Mass Audubon’s Wellfleet Bay Wildlife Sanctuary searches the local beaches for stranded animals. Once a sea turtle is found, responders transport it to the New England Aquarium’s Sea Turtle Hospital in Quincy, Massachusetts.
At the hospital, veterinary teams assess and treat each turtle while closely monitoring its temperature, warming it by about 10 degrees every 24 hours in the holding tanks. With help from the hospital’s rehabilitation partners, most sea turtles return to the wild. The small number that can’t be released stay in professional care.
Cold-stunning rescue stories
A Thanksgiving turtle rescue
Over Thanksgiving weekend in 2020, hundreds of cold-stunned sea turtles stranded along Cape Cod’s beaches after water temperatures fell fast. Teams from Mass Audubon, the New England Aquarium, NOAA Fisheries and volunteer pilots with Turtles Fly Too worked together to move the turtles to rehabilitation facilities up and down the East Coast and along the Gulf of Mexico. Despite weather delays and mechanical setbacks, the turtles safely reached their destinations, where many recovered before returning to the wild.
Image courtesy of New England Aquarium
Sea turtle saved from balloon ribbon
Cold-stunning isn’t the only threat these sea turtles face. While treating a cold-stunned Kemp’s ridley, the New England Aquarium found it had swallowed a balloon ribbon more than seven feet long. Once the turtle was stable, veterinarians removed the ribbon — a stark reminder of what marine debris can do. Research from the University of Queensland has found that more than half of the world’s sea turtles have ingested plastic or other debris, which makes properly discarding balloons, fishing line and other waste one of the simplest ways to help protect these endangered animals.
Image courtesy of New England Aquarium
Are cold-stunning events becoming more common?
Yes. Sea turtle strandings around Cape Cod have increased over the past decade. NOAA Fisheries notes that warming sea temperatures may be influencing turtle movements in ways that raise the likelihood of cold-stunning, though winter conditions, turtle abundance and local geography also shape the size of each event.
How to support sea turtle rescue and recovery
Cold-stunned sea turtles depend on trained responders, veterinary teams and transport partners. There are a few simple ways you can support their work.
- Report stranded sea turtles. Alert your state’s marine wildlife rescue organization, NOAA Fisheries or local authorities as soon as you spot one.
- Keep beaches and waterways clean. Properly dispose of fishing line, plastics, balloons and other marine debris that can entangle turtles or be mistaken for food.
- Support reputable rescue and rehabilitation organizations. The groups that rescue, treat and release turtles rely on public support to keep doing the work.
- Give stranded wildlife space. Always observe from a safe distance. Never move, warm or return a sea turtle to the water unless a wildlife official tells you to.
See more wildlife rescue and recovery stories
Cold-stunning is just one chapter in the larger story of protecting sea turtles. See how experts rescue, rehabilitate and return cold-stunned sea turtles and other animals to the wild in Mutual of Omaha’s Wild Kingdom Protecting the Wild.
Frequently asked questions about sea turtle cold-stunning
Can a cold-stunned sea turtle recover?
Yes. Many cold-stunned sea turtles can recover with prompt rescue and professional veterinary care. Treatment may include gradual warming, fluids, diagnostic testing and care for related problems such as dehydration, pneumonia, wounds or infection.
Why are so many cold-stunned sea turtles found around Cape Cod?
Cape Cod’s hook-shaped coastline can make it difficult for migrating sea turtles to leave the bay as water temperatures fall. Some sea turtles become trapped in shallow, cooling water and eventually wash ashore after they become too weak to swim.
Which sea turtle species are most affected by cold-stunning?
Kemp’s ridley sea turtles are the species most frequently found cold-stunned around Cape Cod. Green and loggerhead sea turtles can also be affected, depending on the location and weather conditions.
Can a cold-stunned sea turtle be released back into the ocean?
Many sea turtles can return to the wild after they’ve recovered and wildlife professionals determine they’re healthy enough for release. The timing varies by animal and depends on its condition, treatment needs and access to suitably warm water.
Sources:
NOAA Fisheries. Cold-Stunning and Sea Turtles — Frequently Asked Questions. Updated June 12, 2026. Accessed July 2026. fisheries.noaa.gov/national/marine-life-distress/cold-stunning-and-sea-turtles-frequently-asked-questions
Mass Audubon. As Stranding Season Begins, Mass Audubon Asks for the Public’s Help in Keeping Sea Turtles Safe. Nov. 10, 2025. Accessed July 2026. massaudubon.org/news/press-room/2025/as-stranding-season-begins-mass-audubon-asks-for-the-public-s-help-in-keeping-sea-turtles-safe
New England Aquarium. Rescued Sea Turtles Receive Font-Inspired Names While Rehabilitating at New England Aquarium Facility. March 11, 2026. Accessed July 2026. neaq.org/about-us/press-room/press-releases/rescued-sea-turtles-receive-font-inspired-names/
