News & Events

An Update on the World’s Most Endangered Turtle

by Rick Hudson 

Gerald Kuchling returned from China recently with news that was not good but not unexpected. The male Yangtze Giant Softshell Turtle (Rafetus swinhoei)¬†at the Suzhou Zoo is not getting the job done. With hundreds of eggs laid since 2008 by the Changsha Zoo female, but without hatching or even¬†signs of fertility, frustration has continued to mount. To try and confirm what we have long expected, we sent Kaitlin Croyle, a research assistant in the Reproductive Physiology unit with San Diego Zoo’s Institute for Conservation Research, to the Suzhou Zoo to examine fresh¬†Rafetus¬†eggs.

Using a technique known as ovo sperm detection, the yolk membranes are removed from eggs in the lab and then stained for sperm and examined microscopically. She was unable to confirm the presence of any sperm, indicating that the male is either infertile, or incapable of inseminating the female.

So what does this mean for the only pair of captive¬†Rafetus¬†left in the world? The Chinese have agreed to allow Dr. Kuchling’s team to attempt to collect semen and try artificial insemination hopefully within the next six months. While this is good news, obviously we need a new male to pair with this prolific egg-laying female. And we believe the best place to possibly find another male¬†Rafetus¬†is in the Red River in Yunnan Province.

For the past two years, Dr. Kuchling has been working with Dr. Rao Dingqi and his students at the Kunming Institute of Zoology, to find and trap another¬†Rafetus. They are using a specially designed collapsible “cathedral trap” that is made for deep water trapping, but tall and buoyant enough to allow the turtle access to the surface. The trap must also be able to adjust to rapidly changing water levels. This from Gerald:¬†Unfortunately, the river’s once turtle-friendly habitat has been transformed by a series of huge hydroelectric dams and reservoirs. The impoundments, with their frequently fluctuating water levels, offer largely unsuitable habitat for the turtles, so any surviving individuals must roam widely.

Repeated Rafetus sightings have been made where side creeks flow into a reservoir downriver of the city of Langsha. These continuing observations may well involve a single individual. Our trapping attempts in the area have failed so far, and are made challenging by rapidly changing water levels that force us to frequently relocate and adjust our traps. Unfortunately, we are not the only people trying to catch giant softshell turtles and locals and recreational fishermen are keen to catch and eat them.

So for now, we find ourselves in a race against time, to trap this turtle – which may well be the key to saving this most endangered turtle in the world – or bear the pain and frustration of seeing it killed and eaten. The stakes could not be much higher.