Record heat results in birth of only female sea turtles in Florida for last four years, scientists report

The temperature of the sand where eggs are nesting determines the gender of most turtles.

Rising temperatures have caused a major spike in female sea turtle births along Florida’s coast, PEOPLE reports.  

According to researchers, every sea turtle born on the beaches of Florida in recent years has been female. 

“Scientists that are studying sea turtle hatchlings and eggs have found no boy sea turtles, so only female sea turtles for the past four years,” Bette Zirkelbach, manager of the Turtle Hospital in Marathon, Florida told Reuters, according to PEOPLE. She also noted that Australia is experiencing a similar imbalance in its sea turtle population.

According to the National Oceanic and Atmospheric Administration (NOAA), the temperature of the sand determines the gender of most turtles. (Photo: Adobe Stock)

According to the National Oceanic and Atmospheric Administration (NOAA), the gender of most turtles is determined after fertilization. Specifically, Reuters reports, the temperature of the sand in which the female digs a nest determines gender.

NOAA notes that eggs incubated below 81.86 F (27.7 C) will hatch males, while eggs incubated above 88.8 F (31 C) will hatch females. Fluctuating temperatures produce a mix of males and females. This phenomenon is called temperature-dependent sex determination (TSD).

Zirkelbach told Reuters that “the last four summers in Florida have been the hottest summers on record,” a situation that she described as “frightening.” 

NOAA has stated that the climate change contributing to rising temperatures that in turn is responsible for the sea turtle gender imbalance will adversely impact future populations. Melissa Rosales Rodriguez, a sea turtle keeper at the Miami Zoo’s new turtle hospital, concurs.

“Over the years, you’re going to see a sharp decline in their population because we just don’t have the genetic diversity,” she said in her comments to Reuters. “We don’t have the male-to-female ratio needed in order to be able to have successful breeding sessions.”

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