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Warming water temperatures may be lulling sea turtles into a false sense of security. They may be more apt to linger farther north than they once did, even though the risk of brutal cold snaps or winter storms is still present. Once hit by cold, they become disoriented and trapped by the hook of Cape Cod, unable to return to warmer waters.
The Gulf of Maine is warming faster than almost any other ocean area on Earth, and a number of other species, including cod, blue crabs, lobsters, and several birds are already shifting their ranges northward or deeper to find cooler waters.
It’s also possible that stronger and more frequent storms, enhanced by climate change, are blowing turtles from drifting seaweed patches in the Gulf Stream into the Gulf of Maine.
In the late 1970’s and eighties, typically fewer than ten turtles would wash up on the beaches of Cape Cod each fall. In recent years, the number of stranded turtles has risen dramatically. Now, it’s common for hundreds to strand. The 2014 season was exceptional—1,200 sea turtles were found on Cape Cod beaches that year and the cause of the spike is still unknown.
Since 1979, staff and volunteers with Wellfleet Bay have been helping to rescue cold-stunned sea turtles. As a part of those efforts, they’ve also been collecting data on where, when, and what type of turtles are stranded. A long term dataset like this is valuable for understanding how sea turtle behavior changes in with the climate.
Much is still unclear about sea turtle behavior, but cold-stun stranding numbers have increased rapidly since the 2000s. While the increase is partly due to better conservation efforts on nesting beaches in Mexico and Texas, those changes don’t explain the magnitude of the increase.
When viewed along with a number of other species being affected by climate change, warmer ocean temperatures and changing currents are a likely factor.
The figure above shows the number of cold-stunned sea turtles recovered by Wellfleet Bay by year. Warm water anomalies likely bring more turtles into Cape Cod Bay in some years (e.g. 2014).
If you are interested in volunteering with Wellfleet Bay Wildlife Sanctuary's sea turtle stranding rescue, or in donating supplies or funds to the program, please visit their website or call 508-349-2615.