(Pictured above, one of the two last known Swinhoe’s softshell turtles (Rafetus swinhoei). This photo was taken in May of 2022 in Dong Mo Lake, Vietnam.)

NEW YORK, January 15, 2025 – Scientists have developed and validated a, first-of-its-kind, portable environmental DNA (eDNA) test to help detect the world’s rarest turtle, the Swinhoe’s softshell turtle (Rafetus swinhoei), which is teetering on the brink of extinction. Two of these turtles are currently known to exist, one wild animal in Vietnam (sex unknown) and one captive male in China (over 100 years old). Additional Swinhoe’s softshell turtles need to be found in order to breed these turtles successfully in captivity and rescue this species.

This new test will help determine if others may still be living in unexplored and understudied lakes, reservoirs, and other large bodies of water. This test, currently being used in the field, can also be adapted to inform field surveys or help find other elusive and threatened species.

EDNA testing was first initiated by the Asian Turtle Program of Indo-Myanmar Conservation (ATP-IMC) in 2013. In collaboration with a laboratory at Washington State University, they obtained the first positive result for the Swinhoe’s Softshell Turtle (Rafetus swinhoei Softshell Turtle DNA in a water sample collected from Xuan Khanh Lake, Son Tay District, Hanoi, Vietnam.

Tim McCormack, ATP-IMC Program Director said, “Our early data showed the feasibility that eDNA testing could be used to detect this turtle species in its natural environment. Although challenging in large lakes and bodies of water, we did have some success with this technique; importantly, this showed that eDNA could be a viable method in confirming additional Swinhoe’s Softshell Turtles in the wild at other locations, with every individual important if this species is to survive.” 

The breakthrough portable DNA test was developed through a multi-year collaborative effort, started in 2016 by the WCS Zoological Health Program based at the Bronx Zoo, WCS Vietnam, in partnership with the ATP-IMC, and the Central Institute for Natural Resources and Environmental Studies (CRES) in Vietnam. The goal of the project was to develop a sensitive and specific portable eDNA water test to detect a known individual of Swinhoe’s Softshell Turtle, confirmed through a previous capture and regular photographing of the individual living in Dong Mo Lake, a massive 3000 acre (1260 hectare) body of water located in the outskirts of Hanoi, the capital city of Vietnam.

Turtles shed their DNA into the environment through urine, feces, and skin cells, but DNA can degrade over time and be diluted in such large water bodies, presenting challenges when detecting in environments with very few individuals. The partners, as noted in a newly published scientific paper in Environmental DNA, explain how the new portable eDNA test kit was successfully applied to detect eDNA from the Swinhoe’s softshell turtle in a massive body of water.

The portable kit uses qPCR technology, which stands for quantitative polymerase chain reaction, and is a technology used for detecting DNA of targeted species. eDNA methodology has been suggested to be one of the most cost-effective approaches to species detection for both enhancing and reducing the cost of traditional survey methods, with traditional methodologies particularly challenging for very rare species. However, most eDNA methods require transporting samples to specialized laboratories, leading to long lag periods between sample collection and result reporting.

Said Dr. Minh Le, Head of Department of Natural Resources and Conservation -  CRES:  “The portable eDNA test has allowed conservationists to be trained in and carry out the qPCR testing in real-time on the ground. This also bypasses the need to export the samples out of the region or country to specialized labs. This project has also enhanced our in-country lab capacity to undertake additional testing that is needed to confirm results.” 

As of 2024, with two known Swinhoe’s softshell turtles, one (male) at the Suzhou Zoo in China and the other (sex unknown) in Xuan Khanh Lake, Vietnam, the only hope for the long-term survival of this species is finding additional, as yet undiscovered animals that have thus far eluded detection by traditional survey methods. Teams are continuing to use this new test in additional lakes in Vietnam to hopefully find other Swinhoe’s softshell turtles.  Previous attempts with artificial insemination several years ago with a captive male and female, both over 100 years old, at the Suzhou Zoo in China were unsuccessful, and the female at the zoo died in 2019.

Dr. Tracie Seimon, Director of the WCS Zoological Health Program’s Molecular Laboratory and lead author of the paper, said: “This project proved that we could use eDNA to detect an extremely rare species in a very large lake, and demonstrates that portable eDNA testing can be applied as a conservation tool to help detect the rarest of the rare of species in a natural environment. This is truly groundbreaking for conservation research.”

Said Thuy Hoang, Director of WCS Vietnam and a co-author of the Environmental DNA paper: “The goal of this study was to develop a test that conservationists can use to enhance our survey work by shortening the time needed to confirm the presence of a species at a site. In addition, we learned from our study that pooling multiple samples together from one habitat before testing is a cost-effective strategy to enable detection over a much larger area while using fewer tests. We plan to continue eDNA testing in our search for the Swinhoe’ Softshell Turtles in other unexplored and understudied lakes with the hope of finding more individuals. By finding other individuals, we may succeed in our overall goal, which is to prevent the species from going extinct.”

The authors emphasized in their report: “Using this test can expand the search for R. swinhoei in unexplored and understudied lakes, reservoirs and other bodies of water where this species may be present and could inform field surveys utilizing eDNA for other threatened species that are rare in nature.”

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