Oh Mother! Why we should be protecting large female sea turtles

A new study by an international team of researchers, including one from the Australian Institute of Marine Science has found that size does matter when it comes to nesting female sea turtles.

The finding, published in Global Ecology and Biogeography, showed that the body size of the sea turtles can influence population dynamics because larger females have greater reproductive output.

Dr Diego Barneche, an ecological statistician at the Australian Institute of Marine Science and adjunct senior researcher with The University of Western Australia’s Oceans Institute, said researchers found female size is a strong predictor for the number of eggs and size of the hatchlings when born.

“Females as they grow older, become what you could call ‘super mums’, contributing more to the population by having more eggs and of a greater size,” Dr Barneche said.

Dr Nicholas Wu, the first author of the study, said the size and number of the hatchlings is especially important when they’re making the dangerous journey from nest to the open ocean.

“That’s because there is safety in numbers and larger hatchlings also have more ‘run power’ to help them escape predators,” Dr Wu said.

“Our work highlights the need to account for body size when predicting how sea turtle populations are being impacted by human activity and also the need to protect large females so that numbers may be more quickly replenished as part of conservation efforts,” Dr Barneche added.

 

The researchers compared two different data sets to estimate how size of female sea turtles contribute to reproductive output– the first a global meta-analysis which is a statistical analysis that combines the results of multiple scientific studies.

“We compared the meta-analysis results with those obtained from a massive dataset of green turtle nesting surveys collected over more than 25 years by the Sea Turtle Research Unit at the Chagar Hutang Turtle Sanctuary in Malaysia,” Dr Barneche said.

“The contributions of female size to reproductive output we saw were similar between datasets, which gives us confidence that, in the absence of local studies, our global meta-analysis estimates serve as a good first approximation to predicting the potential contribution of larger females to population replenishment.

“All the evidence is showing that we should be protecting these super mums, they’re the hope for the future and conserving them can have a lasting impact on the future diversity and resilience of these iconic species.”

Feature image courtesy of Britten Syd Andrews