Climate change impacts
Loggerhead turtle eggs hatch after about two months incubating in warm sand with a temperature range of 24-32℃. Eggs cannot hatch if they are exposed to temperatures outside this range for extended periods. On the Ohama coast in Tokushima Prefecture, where loggerhead turtles come to lay and nest their eggs, the sand temperature has significantly exceeded 33℃ in July and August, and the hatching rate has been conspicuously low in the last 10 years. Sand temperature is important, as during incubation it determines the sex of the turtle.
Adaptation activity
Efforts are therefore being made to reduce the temperature of egg chambers and raise the hatching rate along the Hiwasa and Ohama coasts. Temperatures are regulated by ensuring that the sand is always wet, or by covering egg chambers with a light-shielding net that provides artificial shade. These measures have resulted in an improved hatching rate. In particular, in 2017, the second year of the scheme, despite ongoing high summer temperatures, the rate was 70%, well above the previous average of 54%.
Details appear in Local Adaptation Interview.
