It would appear that once again, this year’s attempts to breed two captive Swinhoe’s soft-shell turtle (Rafetus swinhoei), the world’s rarest freshwater turtle, have hit a wall. This situation has become even more dire after it was announced in January 2016 that the Sword Lake Turtle, one of the only four individuals known to exist in the wild or captivity, had been had been found floating dead in Hoàn Kiếm Lake in central Hanoi, Vietnam.
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 (until this year): one in Hoàn Kiếm Lake (now deceased), 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 in 2014 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, in the spring of 2015 researchers attempted what had until recently been considered by stakeholders too controversial – artificial insemination.
In April 2016, the Turtle Survival Alliance reports that herpetologist Gerald Kuchling oversaw a surgical artificial insemination attempt that injected the semen directly into the female’s oviducts while the turtle was anesthetized. Kuchling was able to closely examine the male’s penis during past insemination attempts and found that it had been mangled, possibly during an ill-fated encounter with a second captive male several years ago. Last year’s attempt involved depositing the sperm into the anesthetized female’s oviducts.
As she has in the past, this year the female laid 65 eggs at the Suzhou Zoo. However, when Kuchling candled the eggs in late June, all were found to be infertile.