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Yangtze Giant Softshell Turtle (Rafetus swinhoei)

An Update on the World's Most Endangered Turtle

Rafetus egg check 2Gerald 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.

Rafetus egg check 5

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.

Rafetus egg check 6

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.

TSA Fig 3Repeated 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.

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Field Surveys for Wild Rafetus

RsF12Jun10SuzhouXThe known world population of Yangtze giant softshell turtles (Rafetus swinhoei) presently counts four living specimens: two in separate lakes in the northern part of Vietnam (Red River drainage) and two in China where the only confirmed female from Changsha Zoo is on breeding loan at Suzhou Zoo since 2008, paired with the only surviving male in China. The male at the Suzhou Zoo appears to be very old and, despite many mating interactions over the last years, none of the numerous eggs the female laid annually produced any hatchlings and all eggs of 2011 were infertile.

Several surveys for Rafetus swinhoei took place over recent years in Vietnam, Laos and China. One of the two specimens in Vietnam, probably a middle-aged adult male, was discovered during such a survey in Dong Mo Lake in the Red River drainage in 2007. A survey along the Red River in Yunnan conducted by Conservation International in February 2007 confirmed the historic occurrence of the species in the Red River in Yunnan and listed several individuals which were recorded up to 1998, but could not find firm evidence for more recent captures or sightings.

The TSA funded a fact-finding mission to the Red River in Yunnan in September 2011 to confirm the information and data reported in 2007. Unfortunately, the team (led by Dr. Gerald Kuchling) also did not find evidence of recent sightings of the species. The main goal of their mission was to visit all Forestry Bureaus in Yunnan where Rafetus had been reported in the past to find out about past and current attempts to collect data on the species. They discovered that all Forestry Bureaus were aware of the rare and threatened status and the significance of the species and are monitoring the respective markets where softshell turtles are traded with the aim to rescue any Rafetus which might be offered for sale.

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Rafetus Breeding Attempt 2011

RsM30May11XWith the glass barriers around both ponds at Suzhou Zoo having been completed in the summer of 2010, the male and the female Yangtze giant softshell turtle (Rafetus swinhoei) have roamed together in both the small and the large pond since 24 August 2010. For the first time, the male and the female were together throughout fall, winter and spring. Following hibernation, the male and the female became active on 25 March 2011 when they both were seen basking. Abrasions on the neck and front limbs of the female when she emerged from hibernation indicated mating attempts during fall/winter (the male grabs the neck of the female with his jaws prior to mounting). The turtles' diet in 2011 consisted of pieces of fresh fish with skin and bones, whole freshwater crayfish, freshwater snails, sausages filled with a mixture of fresh, high quality minced fish, freshwater crayfish, prawns, egg shells, vitamin and calcium supplements, and chicken heads and wings. The sausages are readily eaten by both the female and the male, ensuring good nutrition.

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Rafetus Season Ends in Disappointment

RsF12Jun10SuzhouXThe fourth season for the Rafetus breeding project has come to an end, without the results that we were all hoping for.  It seems that out of the 188 eggs laid, none were actually fertilized.  This has put all of us on the project in a bit of a predicament wondering how to proceed next year (note I said how not if.  There is no question in any of our minds that the project will continue, so long as we have these individuals and if there’s the possibility of other individuals out in the wild).

Depsite the fact that we didn’t get any Rafetus hatchlings, progress was still made and questions were answered.  Concerns about the efficacy of the incubators and incubation methods were put to rest when we successfully hatched more than a dozen red-eared sliders under various incubation conditions.  We also obtained 54 Chinese softshell (Pelodiscus sinensis) hatchlings from a local farm to rear in our large breeding tank.  By doing so, the zoo staff were able to learn how to care for softshells and try different feeding regimens to determine what works best.

RsSausagePrep11Aug10xThere were new challenges to be faced this year as well.  While stray cats and weasels are a known problem at the zoo, this was the first year we saw the weasels enter the Rafetus enclosure.  I was quite concerned because they could pose a threat to the eggs and potential hatchlings.  We therefore reinforced the fencing placed around each nest (standard protocol to keep out any unwanted visitors) and that seemed to solve the weasel problem.  Although they were still entering the enclosure, they could not get at the nests or the eggs. 

Even though we try to cover all our bases, there are always things that we cannot predict and subsequently prepare for.  Towards the end of August, Suzhou experience several severe thunder and lightning storms.  No one (human or animal) was hurt but the closed-circuit camera system we had installed was ruined.  The installation company has taken all the cameras and computer back to their factory to determine the extent of the damage and we are currently awaiting their final report before we can decide if the entire system needs to be replaced or if we just need to replace some of the parts. 

Soon, all of the collaborators on the project will meet again to wrap up this season and discuss options for next year.  Despite all the setbacks we’ve faced to date, all are hopeful that the “Year of the Rafetus” will be just around the corner.

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Turtle Behavior - More Than Just Basking

male_on_beachWhen people ask me what I do on day to day basis, they’re often surprised to hear that a lot of it is purely observational. I am by the turtle enclosures making notes on their behaviors. The general response is always “How active can turtles be?” But I think the truth will surprise many.

A good understanding of animal behavior is an important part of any conservation program. By watching them on a daily basis under various conditions, I can get a sense of what’s normal and what isn’t. Sometimes behavioral changes can signal a change in the overall health of the animal. For example, both animals will come out of brumation around March or April and many people assume they are ravenous at this time and will want to eat constantly. The male does eat fairly regularly early on in the summer but will go off his food later on, when the ambient temperatures get really high. The female is the opposite and doesn’t begin seriously eating until after she’s laid a few clutches of eggs and it’s warmer out (around mid-July). If this were to suddenly change, i.e. the male doesn’t eat early in the season or eats during the periods of extreme heat, it may be a warning sign that something else going on.

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Gearing up for Rafetus 2011

Editor's Note: With both the male and female Rafetus up and basking, the 2011 breeding season is upon us and all those involved are gearing up for this year’s work. Emily King will be based at the Suzhou Zoo throughout the breeding season and will be providing blog updates on this critical conservaton breeding project. 
Emily06Jun10SuzhouHi! I’m Emily and I’ve been lucky enough to have worked with the Yangtze giant softshell turtles at the Suzhou Zoo since the female was introduced to the male back in 2008.  For me, there was never any doubt in my mind what I wanted to do when I grew up. I wanted to work with animals, specifically with wildlife or exotic species.  But it wasn’t until I graduated from university that I discovered what so many people already knew – that turtles are COOL.

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Turtles In Trouble

coverClick here  for a PDF version of the full report.

The plight of the planet's tortoises and turtles -- creatures that have roamed the Earth for 220 million years -- has never been greater, according to the newly released report "Turtles in Trouble: Top 25+ Endangered Tortoises and Freshwater Turtles ."  It shows the world's 25 most endangered tortoises and freshwater turtles will become extinct in the next few decades without concerted conservation efforts.

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World's Rarest Eggs Fail to Develop

rafetus_nestingThe female Rafetus nested this year during the night of June 16 (63 eggs), again during the night of July 2 (63 eggs), and laid a third clutch on July 17. All eggs of the first two clutches were numbered and about half of those eggs were artificially incubated (29, 31 and 33 degrees Celsius, various substrates), the other half was left in the nests constructed by the female. The third nest was not disturbed at all and the eggs were left in place, without being handled.

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Back in China - 2010

Dr. Gerald Kuchling recently sent in this update from the Suzhou Zoo in China, where he has returned to spearhead another breeding attempt for the Yangtze giant softshell turtle (Rafetus swinhoei):

A quick update from China: I and Guundie (note: Dr. Kuchling’s wife), Dr. Lu Shunqing (Wildlife Conservation Society) and Emily King (TSA) all arrived in Suzhou on 18 April. The female Rafetus became active for the first time this year also on 18 April 2010, the day we all arrived in Suzhou. The male had showed some activity since 19 March.

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Second breeding attempt for Rafetus swinhoei in China leads to cautious optimism

The epic move of the last Chinese female Yangtze giant softshell turtle (Rafetus swinhoei) from Changsha Zoo to the last Chinese male at the Suzhou Zoo in 2008 resulted in successful mating, producing two clutches totalling over one hundred eggs. Despite this success, unfortunately none of the eggs hatched. About half the eggs of the second clutch were not properly shelled and many cracked during laying. Nutritional deficencies of the long-term captive female – over 70 years in captivity - were most likely to blame for this setback, and apparently caused any fertilized eggs to die early during development.   Despite this disappointment, this event captured the attention of the global conservation community, and the remarkable story was featured in a PBS/Nature special called The Loneliest Animals that aired on April 19, 2009. Click here to view. 

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