The State of the World's Sea Turtles | SWOT

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Cold-Stunned Sea Turtles in 2020-2021– What You Need to Know

Ashleigh Bandimere

On the heels of our SWOT expert Q&A post about a dead leatherback that washed ashore in Denmark, we began to see a spate of articles in the news about cold-stunned and stranded turtles in the waters of the northeastern U.S.

And in early 2021, this phenomenon has reached into the waters of Texas, where a cold snap has led to reports of more than 4,000 cold-stunned turtles, many under the care of past SWOT grantee Sea Turtle, Inc. in South Padre Island.

Here is a round-up of some of the recent news coverage from late 2020 and early 2021:

We called upon SWOT grant recipient and sea turtle rescue expert, Maxine Montello, to comment on this timely topic, and to answer a few questions about the phenomenon.

A cold-stunned Kemp’s ridley sea turtle in Long Island, NY, USA. © Maxine Montello

SWOT: Can you explain the science and the natural history behind the phenomenon of cold-stunning IN SEA TURTLES?

 Maxine: Sea turtles strand (wash ashore) throughout the U.S. and Europe as a result of climate-related cold snaps that typically occur in the late northern latitude fall and lead to cold-stunning, a physiological temperature shock phenomenon similar to hypothermia. Cases have been documented as early as the 1970s. Cold-stunning occurs when sea surface water temperatures drop below 12°C, causing torpor in sea turtles that can render them unable to continue on their natural southward migrations to warmer waters. Prolonged exposure to low water temperatures can leave sea turtles lethargic, unable to feed or to do more than float at the surface, and can even lead to death. Stranding locations of these debilitated animals are correlated with tidal cycles and prevailing winds, and they are found at sea or on shorelines either dead or in various health conditions based on pre-existing ailments and lengths of exposure.  

SWOT: Is cold-stunning a natural or manmade threat to sea turtles?

Maxine: I believe that it is a natural occurrence that is exacerbated by humans. Sea turtles are naturally susceptible to cold-stunning, however stranding numbers are increasing due to human-related factors such as climate change, entanglement, and loss of foraging habitats. Studies have suggested that as the sea surface temperature continues to increase in the Gulf of Maine, for instance, more turtles are migrating further north, which in theory could lead to more turtles cold stunning if they are unable to migrate back south before water temperatures decrease.

SWOT: There are a lot of stories this year about cold-stunned turtles. Is 2020 an especially bad year?  

Maxine: Each year comes with its own factors that contribute to the overall stranding numbers of sea turtles, and 2020 is no different. It is too soon to say if the numbers are going to be the highest ever documented, but so far 2020 is among the top 5 years for total strandings. In addition to high numbers of strandings this year, we are also dealing with impacts from COVID-19. There are many facilities across the U.S. that participate in response, rescue, and rehabilitation of cold-stunned turtles. Some of those are facing pandemic-related hardships including funding decreases and staff and material shortages, and those factors could limit our ability to address this key threat.  

SWOT: How many sea turtles does cold-stunning impact, and what species are affected, and in which areas is it worst? 

Maxine: Hundreds of sea turtles are impacted by cold-stunning events every year in the U.S., and the number is continuing to increase at both state and national levels. There have been years in which we have exceeded 1,000 cold-stunning cases, and this may become a more severe threat in the future. All hard-shelled sea turtle species are physiologically susceptible to cold stunning, and Kemp’s ridleys, greens, and loggerheads are found stranded more frequently. Of those three species, the critically endangered Kemp’s ridley sea turtle is the most frequently observed during the cold-stun season in New England and New York. Cold-stunning has been documented throughout the U.S. East Coast, with both acute and chronic events documented. Acute cold-stun events typically happen in the southern U.S. due to a rapid cold weather snap, during which large numbers of sea turtles are cold-stunned relatively quickly. Due to the short exposure, those animals tend to rehabilitate quickly and can often be released in a matter of days once waters return to acceptable temperatures. Chronic cold-stun events typically occur further north in the late fall, when water temperatures drop seasonally, resulting in a stranding season that usually lasts 6-8 weeks. Sea turtles impacted by chronic cold-stunning are exposed to cold water for longer periods of time and are therefore more likely to be found dead or in critical condition, sometimes requiring long-term rehabilitation lasting 6-9 months. Returning these animals to warmer waters can also be a logistically more difficult task.

SWOT: How can sea turtles' lives be saved from cold-stunning?

Maxine: Response time plays a critical role in the survival of stranded cold-stunned sea turtles. Once they are stranded on a beach, where they can suffer from exposure and predation, their chances of survival decrease significantly. Many of these turtles appear unresponsive at first, but are still alive. It is crucial for these turtles to be transferred to a rehabilitation facility for triage. Though it seems counterintuitive, transport to these facilities in a cold vehicle is also critical to avoid rapid warming. Once admitted, turtles are then gradually warmed over the course of a few days and provided fluid therapy, antibiotics and nutrition. Both short and long-term rehabilitation can be provided, and many sea turtles in the northeast remain in rehab for 6-9 months before being cleared for release. Without the efforts of these dedicated rescue and rehabilitation organizations, cold-stun survival would be minimal.  

SWOT: Does all of this effort (time and money) make a notable impact at the global or population scale for sea turtles?

Maxine: I believe it does. There will always be a huge debate regarding natural selection and the value of rehabilitation of individual animals. However, global sea turtle strandings are frequently the result of human disturbances such as cold-stunning, entanglement, vessel interaction and pollution. Rehabilitation provides them with a second chance and the possibility contribute to future generations of their species. Though the change is not immediate, in some cases past sea turtle rehab patients have been later observed nesting. To me, these small steps represent a positive outcome from our efforts.  

SWOT: How can everyday people help out? Are there roles for volunteers in areas where cold-stunning occurs? And, if so, how can people learn more?

Maxine: People should seek out their local rescue and rehab organizations to see how they can help. At the New York Marine Rescue Center in New York, and in other states, volunteers are trained by staff to help patrol beaches looking for cold-stunned sea turtles. Many cold-stunned turtles survive due to the amazing dedication of those avid patrollers. You can find out more about these trainings through our social medial and website at: www.nymarinerescue.org. In addition, volunteers and interns may be able to help out at their local rehabilitation facility. There are many organizations that rely on dedicated volunteers protect and conserve sea turtles – see how you can join the cause and become a part of their important work!

Maxine Montello has over 10 years of experience working with sea turtles and marine mammals both in the US and in the Caribbean. As the Rescue Program Director for New York Marine Rescue Center, she oversees rescue missions and rehabilitation efforts for pinnipeds, small cetaceans, and sea turtles. She is responsible for developing and advancing novel critical care and response methods for cold stunned turtles.

Relevant SWOT Report Articles:

  1. Horvath, E. 2016. The Deadly Bucket. In SWOT Report—The State of the World’s Sea Turtles, vol. 11: 42-43.

  2. Swingle, S., Deerr, B., Dittmar, J., Koperski, M., Manire, C. A., Melamet, W., Merigo, C., Montello, M., Price, C., Rose, S., Sampson, K., White, A., and Zagzebski, K. 2019. Stranding Networks: Administer the Three R’s in The American Atlantic. In SWOT Report—The State of the World’s Sea Turtles, vol. 14: 40-41.

  3. Pszonowsky, R. D., Rice, N., and Cheney, D. G. 2019. Finding the Keys to Safe Transport of Debilitated Turtles. In SWOT Report—The State of the World’s Sea Turtles, vol. 14: 42-43.

  4. Witherington, B., Bolten, A. B., Mansfield, K. L., Soares, L., Ceriani, S. A., and Putman, N. F. 2019. Atlantic Loggerheads: Why Isn’t the Best Understood Sea Turtle Recovering? In SWOT Report—The State of the World’s Sea Turtles, vol. 14: 13-14.

  5. Wibbels, T., and Bevan, E. 2018. The Conservation Status of Kemp's Ridley Worldwide. In SWOT Report—The State of the World’s Sea Turtles, vol. 13: 32-33.

  6. Wibbels, T., and Bevan, E. 2015. New Riddle in the Kemp's Ridley Saga. In SWOT Report—The State of the World’s Sea Turtles, vol. 10: 14-17. 

  7. Bowen, B. W., and Wallace, B. 2010. How Sea Turtles Have Weathered Past Climate Changes. In SWOT Report—The State of the World’s Sea Turtles, vol. 5: 13-15.

  8. Coyne, M.S. 2006. Plotting Kemp's Ridley's, Plotting the Future of Sea Turtle Conservation. In SWOT Report—The State of the World’s Sea Turtles, vol. 1: 20.