Hatch and release

Wednesday, April 16, 2008

By Jake Nichols

Jackson Hole, Wyo.-It’s time for the daily tank cleaning at the Jackson National Fish Hatchery. Project leader Kerry Granby sinks a cleaning rod into one of the hatchery’s indoor trout tanks and hundreds of Snake River cutthroat scoot to the other end.

“They don’t like us,” Granby said. And that’s just fine with the staff at the fish farm, where every effort is made to keep the fish wild. After all, this is home for some 400,000 trout before they are released every year into one of more than 20 waterways covering 18,000 square miles of Wyoming and Idaho.

The Jackson hatchery is now in the middle of its artificial spawning season. From March until early June, some 1 million eggs will be ‘milked’ out of females and fertilized with the milt or sperm of male trout. Less than half of those go on to become a baby trout or ‘fry.’ After one year at the hatchery, where human contact is kept to an absolute minimum, the trout not selected for the brood program are stocked mainly in Pallisades Reservoir.

“Everything that goes into the Pallisades is as wild as we can make,” said Elizabeth Scriven, a biological science technician and assistant hatchery manager at the Jackson hatchery. Ninety percent of the fish reared at the hatchery will be dumped into the Pallisades. Others are driven off to places like Lower Slide Lake, Grassy Lake, Salt River and Shoshone River in trucks outfitted with tanks to continuously pump oxygen into the water. Once pumped into their new home, bewildered trout often swirl around in place for hours, a normal process indicative of fish trying to fill their swim bladders, Scriven said.

Swirling in place can be serious business to the Wyoming Game and Fish Department. The agency has closely monitored the state’s waterways for ‘whirling disease’ since 1999. Recent news that Myxobolus cerebralis, the causative parasite of whirling disease, was discovered in a fish hatchery in Ten Sleep, Wyo., has state officials worried that the spread of the incurable ailment to other hatcheries, or into the wild, could jeopardize Wyoming’s lucrative fly fishing tourism industry.

Officials do not know yet how the disease got into the Ten Sleep facility, but early indications point toward spring runoff and nearby groundwater. Fish production and stocking out of that hatchery has been suspended. Any trout testing positive in the hatchery will be destroyed. The state-run facility also confirmed it had shipped infected fish to hatcheries in Boulder and Wigwam, Wyo.

It is not the first time whirling disease has invaded Wyoming. In 2005, a hatchery in Story, Wyo., tested positive and 80,000 trout destined for Lake DeSmet were destroyed.

Whirling disease attacks young fish when their skeletons are still cartilage. The parasitic ailment often deforms them and can cause fish to display the tail chasing behavior that gives the disease its name. In addition to causing fish to swim erratically, the disease is often fatal. It has no known health effects for humans. Once established in the wild, eradication of the parasite is nearly impossible. Game and Fish said it never stocks positive fish into the wild.

Rainbow trout are more susceptible to whirling disease than any other species of trout, according to Cody Beers, of the state Game and Fish Department. Still, Scriven and the crew at the Jackson Hatchery never take chances.

“We have a plan in place that most hatcheries implement to keep out invasive species,” Scriven said. “It breaks down different ways in which the disease can be introduced.”
All transport trucks are washed down thoroughly after returning from lakes and rivers. Visitors are the usual suspect when a disease is introduced inside a hatchery. “Someone could go fishing in a whirling disease-positive creek and get a snail stuck on the bottom of their shoes and visit the hatchery and it falls off,” she said.

The Jackson fish hatchery has little to worry about when it comes to the transmission of disease by tourist. Although the facility receives an average of 75,000 tourists a year, they have not been allowed inside the building since 2000, when it was condemned after its roof failed snow load tests. A new facility is in the design phase and should break ground this summer.

The Jackson hatchery is a national fish hatchery under the jurisdiction of the Department of the Interior. The only other national hatchery in Wyoming is located in Saratoga. The Jackson facility was established in 1950 as part of the Pallisades Dam Act, when it became evident that the native cutthroat trout would need assistance.

The Jackson hatchery is unique in that it is situated entirely within the National Elk Refuge and also contains a geothermal, which allows hatchery personnel to warm eggs to 52 degrees in order to speed growth.

Photo by Jake Nichols
Local hatchery offers native cutthroat living assistance, housing and a ride to the lake.

PERMALINK:
Hatch and release | Planet JH News Article: General Environment

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