Crocs sex ratio under scientists scrutiny

CCMB has standardised research methods on crocodiles that would soon establish the survival rate of hatchlings which would go a long way in maintaining the sex ratio of the species

Hyderabad: The future of crocodiles lies on how warm the surroundings are, for environmental factors decide the sex of all crocodile species. With global warming becoming a hard reality and the hatchery at the Nehru Zoological Park (NZP) closed since 1989, research at the Centre for Cellular and Molecular Biology (CCMB) is being closely followed by the scientific community.

While crocodiles lay eggs by the dozen, maintaining the sex ratio of crocodiles is a challenge. Research on reptiles across the world shows that lower temperature favours female alligators and higher temperature favours male alligators, there could be a similar situation with crocodiles where male crocs may outnumber females leading to the reptiles becoming extinct. It is against such a background that the research at CCMB is gaining importance.

Dr Ramesh K Aggarwal, Chief Scientist, Molecular Genetics Lab, CCMB said, “Serious work on sex determination of crocodiles at CCMB started 10 years ago and it is now we are standardising the method of research and exploring genetic factors. We have identified some candidate genes which seem to be important in Temperature-dependent Sex Determination (TSD) mechanism of Indian mugger.”

What the identification of candidate genes does is it helps in knowing whether the Indian climate is suitable for more female or male crocodiles. Dr Ramesh says, “All crocodiles come under TSD and the incubation temperature of the developing embryo seems to be the major regulator of sex.”

In the early seventies, the crocodile population touched rock bottom and was on the threshold of extinction in the Deccan region. Scientists say that once established facts come out, it would make it easy to maintain sex ratio as one would know exactly under what temperatures the hatchlings would take place. Dr Ramesh says, “It took us 10 years to come to a stage where standards are set which makes it easy for further research.”

No space for crocs at the zoo

The authorities at the Nehru Zoological Park have been relocating crocodiles at Manjeera, Krishna and Godavari rivers for the last two-decades for want of space. Gopi Ravi, curator, NZP said, “The lack of space has been an issue. At the moment, there are close to 70 crocodiles that need to be relocated but with the Manjeera going dry, talks are on to let the crocs in the Krishna.” The zoo authorities are waiting for appraisal from Achampet Divisional Forest Officer for the release of crocodiles.

Every year the zoo hands over close to 250 eggs to CCMB. A senior official at the zoo said the national zoo policy envisaged that number of species native to the region (70%), other indigenous species (20%) and the exotic (10 %) respectively were to be included. The commoner exotic species are proposed to be kept out of the collection plan, as a result the zoo looks to translocate chital and mugger.

By:T P Venu