The global population of free-roaming false gharials (Tomistoma schlegelii), a freshwater crocodilian species native to Malaysia, Borneo, Sumatra and Java, is estimated at fewer than 2.500 individuals.1 Little is known about the reproduction of this crocodilian species. False gharials are mound-nesters and females lay small clutches of 13 to 35 eggs per nest.2
Two adult false gharials, a male of unknown age and a 51-year-old female, have been housed together at ARTIS Amsterdam Royal Zoo during 4 years without reproductive success. In March 2017, the male was physically restrained in ventral recumbency and air-lifted on a ladder. The penis was manually retracted and sperm was collected by digital cloacal massage. The viscous sperm ´plug´, recovered from the sulcus spermaticus, was diluted in Hepes TALP and microscopically evaluated. Concentration was low and total motility was estimated to be 30%. Subsequently the female was physically restraint in dorsal recumbency. After confirmation of follicular activity by transabdominal ultrasonography, the spermatozoa were inseminated by manual guidance of a urinary catheter for foals, cranially of the clitoris, where the oviducts open into the cloaca via the vagina. In addition, adaptations to the enclosure were made to enhance the reproductive activity of this species. Since then reproductive activity have been observed in both animals, but no eggs were laid yet.
The authors would like to thank the management and personnel of the ARTIS Amsterdam Royal Zoo for their great assistance with this case report.
1. Bezuijen MR, Shwedick B, Simpson BK, Staniewicz A, Stuebing R. Tomistoma schlegelii. The IUCN Red List of Threathened Species. IUCN. 2014; e.T21981A2780499. doi:10.2305/IUCN.UK.2014-1.RLTS.T21981A2780499.en. Retrieved 14 January 2018.
2. Bezuijen MR, Webb GJW, Hartoyo P, Samedi, Ramono WS, Manolis SC. The False Gharial (Tomistoma schlegelii) in Sumatra. In: Crocodiles. Proceedings of the 14th Working Meeting of the Crocodile Specialist Group, IUCN. The World Conservation Union, Gland, Switzerland and Cambridge, UK. 1998. p. 10–31.