Frigid Waters, Frozen Turtles

NOAA Scientists Help Rescue ‘Cold-Stunned’ Reptiles

Cold-stunned turtles arriving at Gulf World after being rescued in St. Joseph Bay.

Cold-stunned turtles arriving at Gulf World after being rescued in St. Joseph Bay.

High resolution (Credit: NOAA)

Humans aren’t the only species to feel the grip of winter’s cold hand. Sea turtles generally don’t fare too well either. Recently, about 5,000 sea turtles in Florida were literally rendered immobile by cold weather due to a phenomenon known as “cold-stunning.”

Because sea turtles are cold-blooded animals, they assume the temperature of their surroundings: they’re hot when their environment is hot and cold when their environment is cold. When sea turtles are exposed to frigid water temperatures (about 50 degrees F) over a period of several days, their circulatory systems can slow to the point that they become cold-stunned and unable to swim or function properly. 

Shallow Waters Mean Colder Temperatures

NOAA employee Nancy Evou (in purple cap) inspects incoming turtles for evidence of fibropapilloma disease.

NOAA employee Nancy Evou (in purple cap) inspects incoming turtles for evidence of fibropapilloma disease.

High resolution (Credit: NOAA)

According to Barbara Schroeder, national sea turtle coordinator for NOAA’s Fisheries Service, the record-setting turtle strandings in Florida occurred primarily in shallow, inshore lagoons.

“Because the water in the lagoons is so shallow, it cools more rapidly than the open ocean,” she said. “Turtles living in the open ocean were able to move to deeper, warmer waters during the cold weather. Turtles living in the lagoons could not.”

The hardest hit areas were the Merritt Island National Wildlife Refuge in the Cape Canaveral area (with approximately 2,000 turtles affected) and St. Joe Bay in Florida’s panhandle, which lies east of Panama City (with approximately 1,800 turtles affected). Several hundred more turtles also were affected elsewhere throughout the state. Water temperatures in the coldest areas dropped as low as 39 degrees F.

NOAA employees collect data on live green turtle.

NOAA employees (L-R) Ben Higgins, Lyndsey Howell and Michael Judge collect data on live green turtle.

High resolution (Credit: NOAA)

Warm Hearts, Helping Hands

With so many turtles at stake, biologists from NOAA Fisheries Office of Protected Resources, the Southeast Fisheries Science Center, and the Pacific Islands Fisheries Science Center joined forces with the Florida Fish and Wildlife Conservation Commission (FWC) and the U.S. Fish and Wildlife Service (FWS) for a coordinated rescue effort.

Most of the cold-stunned turtles were found during boat patrols conducted by NOAA, the Florida FWC and the U.S. FWS. Normally, sea turtles will flee when approached by a boat. But these stiff, cold-stunned turtles could only float on the surface, so they were easy to find and recover.

Once ashore, the turtles were moved to temporary holding facilities for rehabilitation. State, federal, local agencies and nonprofit conservation groups were essential to this effort. Local businesses provided trucks to help transport the turtles. Local residents showed up with electric blankets to help warm them and sent food to the facilities where rescuers worked through the night. 

Turtles in tank at Gulf World.

Turtles in tank at Gulf World.

High resolution (Credit: NOAA)

“There were so many people and organizations helping in so many ways,” said Schroeder. “NOAA appreciates all of those participants; without their help, the rescue would not have succeeded.”

Sea turtle rehabilitation facilities took in as many animals as possible, but the sheer numbers of the rescued tortoises were overwhelming. Local fish hatcheries stepped in and offered additional refuge by way of temperature-controlled tanks and aquaria.

Although most turtles were released within a week to 10 days, a few had to remain in rehabilitation facilities for longer-term care. Many sustained serious eye injuries from sea birds, which often peck around the eye areas of cold-stunned turtles.

Sadly, hundreds of turtles were either found dead or succumbed to the cold during rehabilitation. However, the massive rescue mission netted thousands of survivors.

Turtles being released from U.S. Coast Guard vessel.

Turtles being released from U.S. Coast Guard vessel.

High resolution (Credit: NOAA)

Search, Then Rescue … Then Research

The Florida turtle rescue provided a rare opportunity for research that would have otherwise been difficult or impossible.

All of the surviving turtles were tagged prior to being released back into the wild. If recaptured, scientists can learn about their growth, movements and other habits and behaviors.

Even those that didn’t survive will contribute to our understanding of the species. Hundreds of dead turtles were autopsied at a NOAA laboratory in Beaufort, NC.

 “The findings will be helpful in assessing the condition of the animals, learning about their health, obtaining baseline data regarding anatomy and learning about the age structure of the affected population,” said Dr. Larisa Avens, Leader of the Sea Turtle Project at the NOAA lab.

To learn about sea turtles, visit NOAA's Fisheries Service Marine Turtles Web site. NOAA logo.