Since Bob, the green turtle, was released on 27 January after eight years of rehabilitation at the Two Oceans Aquarium, the Foundation has actively monitored his development with the public.
“While Bob rides the swirling currents off the Cape coast, we are thrilled to reveal the groundbreaking news that Bob is female,” the Foundation said in a press release.
Dr Bernice van Huyssteen, the Turtle Conservation Centre's turtle doctor, said that sexing turtles is difficult. A simple DNA (genetic) test can identify the sex of most animals. Turtle testing is poor.
Dr van Huyssteen claims sea turtle males and females are genetically identical. Turtles' sexes are decided by the sand temperature in which they hatch: below 27.7 degrees Celsius, males, over 31 degrees Celsius, females.
Temperature-dependent sex determination means turtles' genomes are identical. Future Two Oceans Aquarium blogs will explore how climate change may affect turtle populations and sex determination.
For immature turtles like Bob, sex organ differences are difficult to detect. Turtles' sex organs, ovaries in females and testes in males look identical on ultrasonography before maturity, making sex identification difficult.
After some investigation and consultation, the Two Oceans Aquarium's veterinary team had one more chance to determine Bob's sex before putting her into the ocean.
Dr van Huyssteen utilised a 2015 testosterone study to establish green turtle gender. Male turtles have higher testosterone levels than females. The study was validated as the turtles matured.
On Bob's release day, the veterinary staff obtained blood samples. Dr. van Huyssteen sent the frozen blood sample to a Pretoria endocrine lab for testosterone testing. The team compared Bob's testosterone levels to the study's typical ranges for men and women. Bob's female!
The Two Oceans Aquarium Foundation's Turtle Conservation Centre expected little indication of Bob's future travels before the test findings. Female turtles nest on the same beach every few years, while males spend their lives at sea.
‘’Like Bob, female green turtles nest every two to three years and can lay up to 2300 eggs in their lifetime. We can see Bob coming ashore thanks to her satellite, flipper, and acoustic tags.
This discovery gives Turtle Conservation Centre conservation manager, Talitha Noble, hope for investigation.
‘’We could continue our voyage with Bob if she nests on the shore. We could re-tag her to track her!’’
Dr van Huyssteen echoed Ms Noble’s sentiments. Discovering Bob is a woman was wonderful. Ultrasound has failed to identify her sex. ‘’Finally, an answer!’’
The Turtle Conservation Centre will use this technique to determine green turtle sex. Dr van Huyssteen believes Bob is the first South African turtle to have his sex confirmed by testosterone testing.
Testing testosterone levels on stranded green turtles to determine sex will add to population demography research.
“This will help us understand green turtle conservation and manage species populations. We can follow them and tell the staff where to release rehabilitated turtles with the trackers,” the Foundation said.
Bob's journey emphasises the Turtle Conservation Centre's efforts. Bob, an injured turtle, became an anti-plastic spokesperson and Aquarium favourite. She can now raise green turtles.
After eight years of care, enrichment, and therapy, Bob moved from ‘’unreleasable’’ to perhaps preserving the green turtle species.
Will Bob change his name? “The answer is simple; Bob will always be Bob to our Aquarium family. We think she should stay that way!” concluded Two Oceans Aquarium Conservation and Sustainability manager Helen Lockhart.
IOL Environment