Hatchery breeds Wyoming's rarest toad.
The Wyoming toad's natural range is within roughly a 30-mile (48-kilometer) radius of Laramie. Following a population crash, the toad was listed as endangered, and most of its habitat is now protected as part of the Mortenson Lake National Wildlife Refuge. As is the case with most listed species, the major factor behind the decline was habitat loss. Irrigation out-competed wetlands for water, and matters were made worse by continued drought. Sensitivity to herbicides was a factor, too. Then there's the chytrid fungus (Batrachochytridium dendrobatidis). Chytrid infections seem to play a large role in suppressing the animal, says David Paddock, the lead toad biologist at Saratoga NFH.
As part of the recovery program, Wyoming toads were brought to the Saratoga NFH for propagation. Captive breeding began in earnest in 1999. Since that time, an average of 6,863 Wyoming toads have been released each year. Between 1999 and 2003, Saratoga produced an average of 55 percent of the toads released to face the rigors of the wild in the Laramie basin. Just last year, tadpoles from Saratoga were released onto two new private land sites covered under Safe Harbor Agreements, a wonderful arrangement made possible by the Service's Cheyenne Ecological Services Office and the Laramie Rivers Conservation District.
The Saratoga facility also produces trout for restoration into the wild. Paddock is a fish biologist by training and a toad biologist by necessity. But he says animal husbandry is much the same, whether for trout or amphibians. He keeps toads at the hatchery carefully isolated from the fishes in their own environment, and he adheres to strict protocols to prevent the spread of chytrid fungus or other disease-causing pathogens. Toads with chytrid are cared for with antifungal treatments.
He says it's easier to get the toads tO breed than one might expect. Of the 150 adult toads kept on station, breeding pairs are carefully selected from a studbook--one used by all the participating zoos in the SSP--to maintain genetic integrity. He gets it done, he says jokingly, "with a little wining and dining." Selected adults are paired off in tanks in two inches (five centimeters) of water filled with artificial plants, then injected with hormones to induce production of eggs and sperm. He leaves them to their desires while recorded toad calls play in the background to simulate the competitive breeding that exists in nature. And Wyoming toads are fecund. Three days later, some of the 2,000 eggs start hatching, and in a matter of days to a few short weeks tadpoles and toadlets are forming. They also quickly become crowded, and therein lies part of the reason the Saratoga Hatchery is so important to the toad's recovery. The participating zoos have such limited space that breedings are few--maybe four a year. Because of its space and expertise, Saratoga is able to perform many more breedings each year, 20 or more, and that means more toads released into their native habitat. That expertise, Paddock is quick to note, isn't all in husbandry. The physical plant is irreplaceable. The hatchery is plumbed with a good supply of water, and maintenance man Pat Malone takes care of it all.
Most of the toads are released in the tadpole stage, and about six weeks after eggs are laid they enter the toadlet stage. Toadlets are released in August, giving them a chance to acclimate to the wild and find quarters in small-mammal burrows before the cold Wyoming winter arrives.
Paddock and others at the hatchery continue to improve the toad husbandry techniques. The 2006 breeding season saw a 17.8 percent increase in its hatch rate over previous years. It's probably attributed to how they treated their brood stock toads over the winter. Paddock held select pairs of toads in colder temperatures over winter to more closely simulate the harsh weather they face in the wild. That exposure during hibernation may have cued something physiologically to make the animals more fecund. So, another refrigerated hibernation unit is on the way to the hatchery, and Paddock expects the toads to show even greater reproductive success in 2007.
The Saratoga Hatchery has a long and productive history. Established in 1911, it created the first brood stock of the threatened greenback cutthroat trout (Oncorhynchus clarki stomias). Now, Saratoga is the first facility in the National Fish Hatchery System to hatch and raise an endangered toad. It's making its mark; after the hatchery put toads into the wild, there is evidence of natural reproduction on Arapaho National Wildlife Refuge, a vital step on the road to recovery.
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|Publication:||Endangered Species Bulletin|
|Date:||Feb 1, 2007|
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