On October 11, 2015, the Nashville Zoo was successful in hatching an Eastern Hellbender that was the result of an egg being artificially fertilized with cryopreserved sperm; an achievement that had only been successful once before in an internal fertilizing Tiger Salamander in 2014. Moreover, this Hellbender is the first externally fertilizing salamander to be produced utilizing cryopreserved sperm.
“It’s a pretty big deal for the conservation of this species and all amphibians,” said Dale McGinnity, Ectotherm Curator. “This accomplishment means we can collect and preserve milt (seminal fluid containing sperm) from wild populations without removing Hellbenders from their environment. Cryopreserved sperm may remain viable for hundreds to thousands of years when kept at ultra-low temperatures with liquid nitrogen. ”
Many of the world’s amphibian species are disappearing from the planet due to pollution, habitat loss, and emerging diseases. Hellbenders, along with their close cousins the Japanese and Chinese Giant Salamanders, are the largest amphibians in the world; they are evolutionarily distinct and have remained relatively unchanged since the age of the dinosaurs. All three species are now in decline and may be threatened with extinction unless conservation programs are developed.
The St. Louis Zoo reproduced Ozark Hellbenders naturally in an artificial stream system for the first time in 2011. The following year, Nashville Zoo successfully hatched two Hellbenders using artificial fertilization. The latest accomplishment is one more step in developing assisted reproductive technology (ART) for captive Hellbenders.
Once ART is fully developed, milt collected and cryopreserved from specimens may be used to fertilize eggs to create a genetically diverse group to boost isolated wild populations. In the future, cryopreserved sperm may be utilized to fertilize eggs to repopulate extinct populations. Nashville Zoo staff has already cryopreserved milt from 4 watersheds, which is believed to be the first gene bank developed for any salamander species.
“We really could not have done this alone,” said McGinnity. “Our Zoo’s Amphibian Specialist, Sherri Reinsch, and our Veterinary staff made the project possible. This success would not have been possible without the collaboration other researchers including Dr. Robert Browne, an Australian cryobiologist; Dr. Vance Trudeau, a Canadian endocrinologist; Dr. Joe Greathouse; Dr. Michael Freake; Dr. Brian Miller; Dr. Dalen Agnew; Dr. Carla Carleton; and Dr. Sally Nofs. A special thanks goes to Bill Reeves, the Chief of Biodiversity for the Tennessee Wildlife Resources Agency for the State Wildlife Grant that helped to fund this work which also included statewide surveys, gene banking, disease testing, and genetic work for hellbenders in Tennessee.”