Source: New Straits Times
Date:May 22, 2009
Mating game their last hope
IT was a union that many had waited for with bated breath.
For conservationists, the mating of two Yangtze giant soft shell turtles had to be done to save the species from extinction.
They were paired up between April 26 and May 7 at the Changsha Zoo in Hunan province, China. The male turtle from Suzhou Zoo is believed to be 100 years old and the female turtle over 80 years old. She is expected to nest in early June or July.
This the second time scientists have mated the turtles at the zoo. Last year, the attempt failed when none of the fertilised eggs were able to hatch.
The procedure is being coordinated by the Wildlife Conservation Society and the Turtle Survival Alliance, a global network founded in 2001 focused on protecting endangered turtles.
TSA consultant in reproductive biology Dr Gerald Kuchling hoped this time the eggs would develop and hatch.
"It is important that they breed. They are perhaps the last surviving Yangtze turtles. Three adults, which were among the last few in China, died between 2005 and 2007.
"Hatchlings mean this species will get a renewed chance at recovery," he told the New Straits Times during a recent visit to a river terrapin nesting site in Setiu, Terengganu.
Rafetus swinhoei or commonly known as the Yangtze giant soft shell turtle is the most critically endangered species in the world. Pollution, over-harvesting for Asian food markets and habitat destruction have all been implicated as causes of the turtles' demise.
According to Wikipedia, it may be the largest freshwater turtle in the world. There are only two known to survive in China (the two that are being mated), and in Vietnam another two of the species have been sighted. One lives in Hoan Kiem Lake in the centre of Hanoi, and the other in Dong Mo Lake near Hanoi.
The Yangtze turtle is known for its deep head with a pig-like snout and dorsally placed eyes. It measures more than 100cm in length and 70cm in width and weighs between 120kg and 140kg. The carapace, or shell can grow larger than 50cm in length and width. Males are generally smaller than females and have longer and larger tails.
Kuchling said the failure last year was probably due to a calcium deficiency in the female turtle's diet. Although it had produced roughly 100 eggs, none of the embryos survived and scientists believed they died in early development.
A number of the eggs had very thin or cracked eggshells, which suggested that the turtles' diet was not optimal.
Kuchling said the female turtle had been fed with raw beef and pork, instead of fish and crayfish.
"If the nutrition of the female is not right, the eggs usually die," he said.
Kuchling has since advised officials at the Changsha Zoo to switch to the appropriate diet, including vitamins and calcium supplements.
He said once the turtle had laid her eggs, half of it would be hatched in-situ, while the other half split in three incubators, provided by the TSA, with different temperatures to ensure a balance ratio of male and female.
The sex of a turtle depends on the temperature, where a warmer climate will lead to females and vice-versa.