San Diego Zoo Global Conservationist Flies to China to Examine Rare Turtle Egg

Recognized as the world’s most endangered turtle, the Yangtze giant softshell turtle is dangerously close to extinction, being represented by only four known individuals left in existence.  Two males are in Vietnam and there is one breeding pair protected under human care at the Suzhou Zoo in China – both are estimated to be between 80 and 100 years old.  Although the female  – owned by the Changsha Zoo –  has produced thousands of eggs since she was paired with the male in 2008, none have hatched.  The expertise of San Diego Zoo’s Institute for Conservation Research was requested and, with the support of the Turtle Survival Alliance (TSA) and the Wildlife Conservation Society, a reproductive expert was sent this last summer to evaluate a recently laid clutch of eggs.

“Within days of the female Rafetus nesting, I was on my way to Shanghai,” said Kaitlin Croyle, student researcher with the San Diego Zoo  Institute for Conservation Research.  “After almost 36 hours of planes, trains, and automobiles, I arrived in Suzhou and went straight to work, as I only had one full day in China before I needed to take a flight back to San Diego.”


Katlin Croyle, a student researcher with the San Diego Zoo Institute for Conservation Research checks eggs of the endangered Yangtze giant softshell turtle.

After an extensive examination of eggs using a newly developed technique for assessing the presences of sperm, Kaitlin reported that no sperm were present in the eggs. The new technique, called oocyte membrane-bound sperm detection (OMSD), is being developed for turtle and tortoise species by Kaitlin at the Institute with the hope of assisting in endangered species conservation.  OMSD tests for the presence of sperm in eggs that fail to develop an embryo.  This information, in combination with behavioral observations, reproductive history, and veterinary examination, can be used to make educated decisions about breeding pairs to increase the chance for future offspring.

Although disappointing, the result of the whirlwind trip allows conservationists working with the Suzhou Zoo to make an informed decision with regards to future breeding of the rare turtle.
“With only four giant soft-shelled turtles left in the world it is important to do whatever we can to help this female to reproduce,” said TSA President Rick Hudson.  “Kaitlin’s work has helped confirm the male’s probable infertility and we will work to identify other mechanisms for securing fertile eggs in the future. Our hopes likely hinge on finding another male.”
Bringing species back from the brink of extinction is the goal of San Diego Zoo Global. As a leader in conservation, the work of San Diego Zoo Global includes onsite wildlife conservation efforts (representing both plants and animals) at the San Diego Zoo, the San Diego Zoo Safari Park, and San Diego Zoo Institute for Conservation Research, as well as international field programs on six continents.  The work of these entities is made accessible to children through the San Diego Zoo Kids network, reaching out through the Internet and in children’s hospitals nationwide.  The work of San Diego Zoo Global is made possible by the San Diego Zoo Global Wildlife Conservancy and is supported in part by the Foundation of San Diego Zoo Global.