Genetic testing enables safe release of Siamese crocodiles in Cambodia

For the past three years, the WildGenes programme at the Royal Zoological Society of Scotland (RZSS) has been working with Fauna & Flora International (FFI) and the Royal University of Phnom Penh (RUPP) to develop the first conservation genetics laboratory in Cambodia.

A jewel of biodiversity in Southeast Asia, Cambodia is home to the largest freshwater lake in the region and a myriad of habitat types, from the rainforests of the Cardamom Mountains to the wetlands of the Mekong River. Conserving the remaining diversity is vital and using conservation genetic tools could greatly help. By putting these genetic tools in the hands of the people who live and work within the country, RZSS WildGenes aims to provide long-term capacity for future conservation management.

One species that is already benefitting from this partnership is the critically endangered Siamese crocodile. One of the rarest crocodiles in the world, it was pushed to the brink of extinction in the 20th century before the last remaining populations were discovered by FFI in 2000.

Smaller and much more docile than many of its relatives, the Siamese crocodile is revered by some indigenous communities. Indeed, the Pearic people of the Cardamom Mountains believe that crocodiles represent their ancestor spirits; this protection may have been critical to the persistence of the last populations here.

Siamese crocodile habitat, Cardamom Mountains, Cambodia. Credit: Jeremy Holden/FFI

Elsewhere, the Siamese crocodile has had to contend with severe habitat degradation and extensive poaching for the leather industry. Even as the last wild populations were going extinct, thousands were being bred in farms for their skins. Now, it is these captive individuals that may hold the key to the future survival of the species, with just one caveat.

Crocodile farms usually keep many different species together and purposely hybridise them to ‘improve’ the leather quality. This means that many of the Siamese crocodiles that were brought to these farms have been bred with larger, more aggressive species, such as the saltwater crocodile.

The only way to determine which individuals are Siamese crocodiles is by genetic testing. RZSS WildGenes has now developed a genetic test to do just that, and scientists based at RUPP used it for the very first time last year. This now means they can test farmed crocodiles to identify which individuals can be released back into the wild.

Genetic analysis of a Siamese crocodile blood sample. Credit: Catfish/FFI

Once species identity has been confirmed, the crocodiles will join the 111 Siamese crocodiles already released as part of FFI’s long-term work to conserve the species. Ongoing biological monitoring and habitat patrolling then provides vital information about how the crocodiles are faring in the wild.

We are extremely proud to be part of this vital work and I made sure to visit FFI’s Siamese crocodile breeding programme at Phnom Tamao Wildlife Rescue Centre on my recent training trip. I was privileged to see this year’s cohort of young hatchlings and they did indeed bring a huge smile to my face. So, forget what you may have heard, these crocs are something to smile about.

This article has been adapted from the original version which you can find on RZSS’s website here.