The Southern River Terrapin (Batagur affinis) is a species of riverine turtle classified under the family Geoemydidae. This species inhabits the lower Peninsular Malaysia and Sumatra and is conspecific with the northern species. An adult B. affinis can grow to an average weight of 20-25 kg (max 36 kg) and a carapace length of 62.5 cm. It can be distinguished from most other large riverine geoemydids in its range by having four claws on its forefeet instead of five, and by having two longitudinal denticulated ridges on the triturating surface of its upper jaw, rather than just one. This terrapin has a deep, massive, heavily buttressed shell, large powerful limbs, broad fully webbed feet, and a skull with serrated tomia and a broad triturating surface.
The taxonomic status of the Southern River Terrapin can be evaluated through phylogenetic analyses of three mitochondrial and three nuclear DNA fragments, comparing them with all other Batagur species. The genetic results indicated that Cambodian Batagur is closely related to but distinct from B. affinis found in Sumatra and the west coast of Peninsular Malaysia. Morphologically, Cambodian Batagur resembles the distinctive B. affinis populations from the east coast of Peninsular Malaysia, which were not included in the genetic study. As a result, the unnamed Batagur populations from the east coast of Peninsular Malaysia and Cambodia were categorized as a new subspecies, i.e. Batagur affinis edwardmolli, which presumably once inhabited estuaries around the Gulf of Thailand. Batagur affinis edwardmolli is noted for having a narrower and sharper snout compared to B. a. affinis, although this distinction has not been precisely measured. The skin at the back of the head is divided, forming several irregularly shaped scales. The upper jaw is bicuspid, while the lower jaw features a central cusp complemented by shallow notches on each side. The choanae are partially covered by a flap that bears a small papilla.
The Southern River Terrapin is heavily exploited for their eggs and faces habitat destruction. In Thailand, the species is nearly eradicated. In Malaysia, threats include dam construction, egg harvesting, vegetation removal, sand mining, and poaching for human consumption. Despite legal protections, organised egg exploitation and poaching persist. Habitat destruction from sand mining, dam construction, deforestation, and siltation impacts nesting and feeding areas. Developments like highways and shrimp farms introduce light pollution, chemical effluents, and salinization, further harming the terrapin’s habitat.
Several steps have been taken to conserve the Southern River Terrapin in Malaysia. One of these is the establishment of hatcheries. The Department of Wildlife and National Parks (DWNP) in Malaysia set up the initial hatchery for the terrapin on the Perak River in 1967. This hatchery aimed to increase the survival rates of terrapin eggs and hatchlings. In the next decade, the DWNP expanded its conservation initiatives to rivers beyond Perak, including the Kedah and Terengganu Rivers. These efforts demonstrate a long-standing commitment to safeguarding the terrapin population.
Furthermore, Malaysia has also implemented a head-starting programme for terrapins, which involves raising hatchlings in captivity until they reach a size where their survival in the wild is enhanced. By releasing these juveniles into their natural habitat, the programme aims to bolster wild populations. Conservation efforts in Malaysia also include protecting major nesting areas of the Southern River Terrapin by banning egg collection from the wild and increasing hatchling success through beach patrolling to deter predators. TCS initiated a community-based river terrapin conservation project in 2011 to restore the depleted terrapin populations in the Kemaman River. To date, we have saved more than 8,200 eggs from human consumption, and released more than 4,600 head-started terrapins into the Kemaman River. Without this project, all 8,000 eggs would have been eaten by the local communities. Lastly, conservation measures include regulating and prohibiting sand-mining activities in rivers where terrapins occur to safeguard nesting sites, particularly in Terengganu. To this end, TCS conducts fortnightly river surveys to identify threats and remove abandoned/discarded fishing gear from the river to prevent the accidental entanglement of river terrapins and other wildlife.
References:
- Praschag, P., Sommer, R.S., Mccarthy, C., Gemel, R. and Fritz, U., 2008. Naming one of the world’s rarest chelonians, the southern Batagur. Zootaxa, 1758(1), pp.61-68. PDF
- Praschag, P., Holloway, R., Georges, A., Paeckert, M., Hundsdoerfer, A.K. and Fritz, U., 2009. A new subspecies of Batagur affinis (Cantor, 1847), one of the world s most critically endangered chelonians (Testudines: Geoemydidae). Zootaxa, 2233(1), pp.57-68. PDF
- Chen, P.N., 2017. Conservation of the Southern River Terrapin Batagur affinis (Reptilia: Testudines: Geoemydidae) in Malaysia: A case study involving local community participation. Journal of Threatened Taxa, 9(4), pp.10035-10046. PDF
