San Diego Zoo Researcher Examined Rare Turtle Eggs in China

A San Diego Zoo researcher flew to China to examine the egg of one of the world’s most endangered turtles last year.

Kaitlin Croyle, a student researcher with the San Diego Zoo’s Institute for Conservation Research, flew to China to examine the eggs of one of four remaining Yangtze giant soft shell turtle.

Only four known individuals are left in existence, two male turtles in Vietnam and one breeding pair protected under human care at the Suzhou Zoo in China. Both of the breeding pair are estimated to be between 80 and 100 years old.

The female turtle of that breeding paid has produced thousands of eggs since she was paired with the male in 2008, but none of those eggs have hatched. The Chinese zoo requested an expert from the Institute for Conservation Research 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."

Croyle’s evaluation used a newly developed technique, oocyte membrane-bound sperm detection, for assessing the presences of sperm and determined that no sperm were present in the eggs.

The technique is also being developed for turtle and tortoise species by Croyle at the Institute to better help with endangered species conservation and Croyle's findings will now help the Chinese zoo make informed decisions about the breeding future 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 Turtle Survival Alliance 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."

The San Diego Zoo Global is a world leader in working to bring species back from the brink of extinction.

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