Swinhoe’s Softshell Turtle: Captive Breeding Program 2015 Update

The annals and magazine of natural history : zoology, botany, anWith news coverage of this year’s attempts to breed Swinhoe’s soft-shell turtle (Rafetus swinhoei), the world’s rarest freshwater turtle, hitting the pages of the New York Times this month, it would appear scientists aren’t the only ones tuning in to see what fate his in store for a species for which there are only four individuals known to exist in the wild or captivity today.

Swinhoe’s softshell turtle has long been famous for it role in Vietnamese legend as the fabled Sword Lake Turtle, which inhabits Hoàn Kiếm Lake (“The Lake of the Returned Sword”) in Hanoi, Vietnam. But of the handful of Swinhoe’s softshell turtles known to scientists to exist in the wild or captivity in recent years, five have died since the 1990s, leaving only four remaining: one in Hoàn Kiếm Lake, one in the wild in Đồng Mỏ Lake west of Hanoi, and two in captivity, the latter now both part of the Suzhou Zoo’s captive breeding program.

Since 2008, when the Changsha Zoo’s female, “China Girl,” was relocated to Suzhou, scientists at Suzhou Zoo have undertaken a captive breeding program with their older male turtle. But despite repeated bouts of courtship displays and mating between the pair in the years since, the resulting eggs have failed to hatch. Remediative actions to date, including steps to improve their diet by constructing a glass wall to prevent visitors from tossing junk food into their inclosure, provisioning the pair with a more natural diet (e.g. whole shrimp, freshwater crayfish, fishes, freshwater snails, frogs, quail, pigeons), and redesigning their enclosure to allow the pair more time together, have proven unsuccessful.

After the Suzhou Zoo’s captive breeding program reported last fall that their male may be infertile, the future of the program and the species were both at risk. In a move that lets slip their growing concern for the species’ survival, researchers this spring attempted what had until recently been considered by stakeholders too controversial – artificial insemination.

On May 6th, herpetologists Gerald Kuchling with the Turtle Survival Alliance and Lu Shunqing with the Wildlife Conservation Society’s China branch, together with a team of specialists, anesthetized the Suzhou male and – with a stack of car tires as an examination table – used an electrical probe to extract sperm. In doing so, the team was also able to closely examine the male’s penis and found that it had been mangled, possibly during an ill-fated encounter with a second captive male several years ago.

Although the sperm showed low motility, they were otherwise deemed viable and were deposited in the sedated female’s oviducts. However, with so little known about the reproductive physiology of turtles and tortoises, much less the Swinhoe’s softshell turtle, only time will tell whether this year’s attempt proves successful.

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