Successful sex identification of marine mammals

19 March 2021

Faculty of Veterinary Medicine

The Faculty of Veterinary Medicine and the Phuket Marine Biological Centre, Department of Marine and Coastal Resources, Ministry of Natural Resources and Environment have succeeded in developing a sex identification technique for dugongs, whales, and dolphins using a molecular biology technique, which would be greatly beneficial to data collection regarding marine mammals.

The population of marine mammals such as dugongs, whales and dolphins is now endangered and these animals are protected by several laws, including The Fisheries Act, B.E. 2490 (1947), National Park Act B.E. 2490 (1947), and Wildlife Conservation and Protection Act, B.E. 2535 (1992), as well as The Convention on International Trade in Endangered Species of Wild Fauna and Flora. When the bodies of dead marine mammals are found floating in the ocean, identifying their sex is sometimes not possible due to the severely decayed state, hence the need for the present study and technique.

Assoc.Prof. Dr. Korakot Nganvongpanit from the Faculty of Veterinary Medicine, CMU, explains that using molecular biology techniques to identify the sex of animals, including humans, has been extensively researched and practiced. However, in marine mammals, previous studies are limited to specific animals, so this research applied the findings from those studies to come up with a technique that is applicable to several species, without requiring a specific primer for one particular species. To put it simply, with only two pairs of primers, with the first pair for the X chromosome and the other for the Y chromosome, this technique can be performed for various species. So far, it has helped the Phuket Marine Biological Centre identify the sex of 48 specimens, which included 3 dugongs, and 45 whales and dolphins

Results of SRY and ZFX gene identification. SRY gene is only found in male and ZFX in both male and female. No 1 – 3 in the picture show both SRY and ZFX genes, indicating that it is male.

Dr.Kongkiat Kittiwatanawong, Director of the Phuket Marine Biological Centre, adds that other important biological data of these stranded animals – location of discovery, species, sex, and size, have to be recorded, but a problem that the team frequently encounters is that the state of the body prevents sex identification. With this technique, all the required data can be obtained, and it will be useful for analysis in other domains. Henceforth, the sex of dugongs, whales or dolphins can be identified and contribute to marine biology research.