Siamese crocodiles re-introduced in Cat Tien National Park

Posted on January, 14 2002

No Siamese crocodiles had been seen in Cat Tien National Park for 7 years until the recent reintroduction.
Ho Chi Minh City, Vietnam - 10 Siamese crocodiles (Crocodylus siamensis) have been released in the Bau Sau wetlands in Cat Tien National Park. The release site is known to have harbored large numbers of these crocodiles in the past but none have been observed over the last 7 years.

All the crocodiles have been hunted for food and for breeding in crocodile farms in southern Vietnam. With the assistance of the WWF - Cat Tien National Park Conservation Project, Cat Tien National Park aims to re-establish a wild population in its Bau Sau wetlands.

The crocodiles which have been released are part of a larger number donated by Hoa Ca crocodile farm in Ho Chi Minh City. All animals have been DNA tested at Queensland University - Australia to assure that they are of pure C. siamensis breed.

Crocodile farmers prefer to mix their C. siamensis breed with Cuban or Saltwater crocodiles as the offspring produces a better quality leather. As offspring remains fertile, an individual crocodile could be 1/4 Cuban and 3/4 Siamensis or 1/2 Siamensis and 1/2 Saltwater, etc. and there are no morphological differences to be seen from the outside. Therefore DNA testing is the only way to separate pure from non-pure C. siamensis.

The contact with Queensland University ran through Dr. Phan Viet Lam of the Saigon Zoo, who took the blood samples and inserted a chip in each sampled crocodile. On December 18 2001 Dr. Phan Viet Lam read the chips and linked the individual crocodiles to the DNA test results. Of the tested animals, one was found not to be of pure C. siamensis breed and this animal was rejected from the re-introduction programme. In total 10 (5 males and 5 females) pure C. siamensis were transferred to the Bau Sau wetland area and released back into the wild.

About 25 more crocodiles remain at the headquarters of Cat Tien National Park, most of which are yet to be DNA tested. These animals will be released over an estimated period of 3 years. Members of the IUCN-SSC Crocodile Specialist Group provide technical advice for this programme.

Post release activities include the regular monitoring of the crocodiles to see whether they remain in the area or will disperse over a larger area. The Park's Forest Protection Department will step-up its law enforcement operations in the area to deter potential violators. Plans are prepared to distribute information on the biological importance of the crocodiles targeting people who live in the vicinity of the wetlands.

For more information:
Nguyen Diep Hoa, WWF Indochina Programme Office, email: