Yellowstone Cutthroat Trout were spawning in Lovell Tuesday morning. No, not in a local stream, but rather in the parking lot at the Bighorn Canyon National Recreation Area just east of town.
A new program to better time the spawning of the cutthroats as part of a program by the Wyoming Game and Fish Dept. to increase genetic variability of the native fish was launched this year, and the first stage was conducted Tuesday.
According to Pat Long, assistant superintendent of the Tillett Springs Rearing Station northeast of Lovell, when fish are separated from the wild as brood stock, the genes of the stock gradually begin to alter over time and genes from wild fish must be introduced to the population. He said the fish are tested at a lab in Bozeman, Mont., every five to seven years to check their genetics and make sure the fish DNA has not drifted from the natural population.
In the past, the taking of cutthroat eggs and milt (semen) would be collected in the wild in Yellowstone streams, Long said, with Game and Fish personnel catching as many pair of fish as they could, up to 150. But with wood ducks nesting in the spawning areas, Clear Creek and the LeHardy Rapids, the Game and Fish hasn’t been able to catch the fish run at prime time.
The Game and Fish came up with what the agency hopes is a better plan – moving female brood stock from the Ten Sleep Hatchery to the colder water of the Story Hatchery and keep them there for a year as their system adjusts to the water that can get as cold as 35 degrees. The idea is to time the spawn with the availability of the male cutthroats in Yellowstone, Long said, slowing the females down to match the wild run of the males in Yellowstone.
On Monday, the Game and Fish used dip nets to capture and collect milt from 51 males in Yellowstone. The milt was transported to Lovell Tuesday, there to fertilize eggs from female fish brought to the Park Service parking lot from Story. Long said 22 females were viable on Tuesday.
On site, eggs were excised from the females into a plastic basin, and quickly two teaspoons of the bright, orange eggs are carefully scooped into small bowls where milt is introduced. Two teaspoons of eggs from each female are fertilized with milt from two different male fish.
It only takes 45 seconds to one minute for the eggs to be fertilized, after which the eggs were gently rinsed and placed in a cooler to be water hardened. Long said the eggs absorb water for two hours and can then be transported to the rearing station because the water absorption makes the eggs hard.
“They’re about as bulletproof as you can get them,” he said.
About 4,800 eggs were collected during the spawning operation, Long said.
Long drove the eggs to the rearing station, disinfected them with iodine and placed them in an isolation facility for rearing. It takes the cutthroats about 14 days to reach the eyed stage, and then they can be handled again and will hatch in another 12 days.
“We raise ‘em up through the sack stage and feed them,” he said. “Then we raise them to about two inches (in length).”
The fish are tested at a lab in Laramie, and if the fish are disease free, they are moved to Game and Fish culture section facilities and raised up in the hatcheries to be used as brood recruitment fish. The current crop of fish will likely go to Ten Sleep, Long said.
The fish with their wild genes will cycle in with the fish at Ten Sleep, increasing genetic variability, Long said. It’s all part of an ongoing effort to preserve the native cutthroat population in Wyoming.
This is the first of three years the spawning method will be tried.
“Our goal is to breed 150 pairs each year, but we’ll do 250 for leeway,” Long said. “We’ll do it over a three-year period.”
Working with the fish Tuesday were Long, Wyoming Fish Culture Supervisor Steve Sharon, Assistant Fish Culture Supervisor Guy Campbell, Ten Sleep Hatchery Supt. Bart Burningham and Story Hatchery Supt. Steve Diekema.
By David Peck