Probing the life stages, strandings of sea turtles
The Sanibel-Captiva Conservation Foundation’s Sea Turtle Program is focused on ensuring the survival of sea turtles through nest monitoring, research, education, training, advocacy and habitat protection. Achieving these goals is becoming increasingly complex in the face of coastal development, climate change, ocean plastics, habitat loss and a wide variety of emerging and worsening threats, officials said.
In addition to the identifiable threats, there are also some profound mysteries that sometimes stymie sea turtle conservation efforts.
“Our brief experience with them on the beach provides an important glimpse into their lives, but relatively little is known about sea turtles from the time the tiny hatchlings enter the open ocean until they return 25 to 30 years later to nest as adults,” SCCF Coastal Wildlife Director Kelly Sloan said. “Where do they go when they leave? What route do they take to get there? Where and when are human activities more likely to affect their survival and their health?”
Understanding sea turtle behavior at each of their life stages is critical for ensuring their survival. Satellite telemetry has been used widely to explore these mysteries by tracking their movements at sea and has had profound impacts on in-water conservation efforts, connecting life history, ecology and hazardous intersections for turtles. SCCF staffers have deployed 17 satellite tags on loggerhead and green sea turtles to help make these connections for the turtles nesting in Southwest Florida.
An unfortunate but important way to learn more about the in-water threats they face is by documenting the sources of morbidity and mortality in strandings — sea turtles that are found dead, sick or injured. The Sea Turtle Stranding and Salvage Network is a cooperative effort comprised of federal, state and permitted private partners along the coast from Maine to Texas. STSSN participants report sea turtle strandings to a centralized database so that trends and emerging issues can be identified and addressed.
In the decade preceding the 2018 red tide — from 2007 to 2017 — an average of 31 strandings were reported annually by the SCCF on Sanibel and Captiva. During the red tide event, that number skyrocketed to 20 — with an additional 51 reported by the Clinic for the Rehabilitation of Wildlife. In 2019 and 2020, stranding totals were 55 and 41, respectively.
The species composition in 2020 was 23 loggerheads, comprising 56 percent; 15 green turtles, making up 36 percent; two Kemp’s ridleys; and one unidentifiable species due to its state of decomposition. Boat strikes at 13 and predation at 15 represented the most significant source of mortality last year. It is unknown if the injuries occurred pre- or post-mortem. In six strandings, there were no obvious injuries, and the cause of death could not be determined using external evaluation alone.
Each of these life-cycle puzzle pieces has guided strategic sea turtle conservation for decades.