Traveling trout get help acclimating to alkaline waters
All this month, tens of thousands of young Lahontan cutthroat trout fingerlings will be traveling across the Carson Valley on their way to eventual freedom in either Pyramid or Walker Lake.
No, they’re not swimming upstream, they’re going by tanker truck.
These fish are lucky enough to be the beneficiaries of a relatively new gradual acclimation innovation which has cut mortality from a high of 90 percent to what is now 5 percent or less, according to Lahontan Fish Hatchery supervisor Larry Marchant.
“We were having high mortality with our fish when we put them directly into Walker Lake from the hatchery,” he said. “Walker is highly alkaline, so the chemical change really shocked them and took a toll.”
Figuring out how to get young fish grown in the clean, fresh Valley well water they grow up in at the hatchery, to the highly alkaline lakes without shocking them to death was the key to saving them.
Marchant said the drought years and over-allocations of water from the Walker River coming into Walker Lake, turned it into one of the most alkaline lakes in the area.
Someone noticed that the fish from the fish hatchery run by the Paiute Tribe on the shores of Pyramid Lake – half as alkaline as Walker, but still much higher in alkalinity than the water at the Lahontan Fish Hatchery – fared quite well when they went to Walker Lake.
So, in a cooperative effort between the tribe, the state of Nevada and the Lahontan Fish Hatchery, which is run by the federal government, a plan was devised four years ago to gradually acclimate these delicate fish, rather than plunging them directly into such a chemically different aquatic environment.
– On the road. The trout distribution season, which began Monday, involves one truck per day taking approximately 20,000 fish from the Valley hatchery to Pyramid Lake, where they are placed into the lake water at the hatchery for one week.
The tankers are equipped with four water tanks, each holding 600 gallons of water, with liquid oxygen aerators, hoses and pumps serving to keep the young fish healthy for the nearly two-hour drive. The tanker driver must stop at designated spots to check the fingerlings and make sure everything is functioning correctly.
Some of the fish, around 325,000, will eventually stay at Pyramid Lake and grow as big as 15 pounds in 8 to 9 years. The record fish caught there many years ago was 40 pounds and is on display at the state museum in Carson City.
The rest of the fish, approximately 110,000, will go from a week in Pyramid directly into Walker Lake. These fish will not get as big as the Pyramid Lake fish, but should grow to around 8 pounds, Marchant said.
The Truckee River also gets fish, approximately 50,000, which will be delivered later this year, he said.
As soon as all the fish are released, their places at the hatchery will be filled by new fish who are hatching out of eggs spawned this spring.
“We have to get the bigger fish off station to make room for the new ones,” said fishery program assistant Judy Saferite.
– The cycle. This year’s releases will be too small to catch when the 1999 fishing season gets under way – they are only 6 inches long now – but by the millennium they may reach catchable size.
The majority of the eggs used in the fish hatchery growing cycle will come from Pyramid Lake, Marchant said.
“Next year, we’ll take 1.1 million eggs,” he said.
To get the eggs, biologists anesthetize the females, collect the eggs and then release the moms. The males also get released after giving their “milk,” so these fish can be productive for many years.
Last year, 30,000 Pyramid-grown fish returned up the spawning channel in the Pyramid hatchery on their own.
Marchant said the strain of what is hoped to be genetically pure original Lahontan cutthroat trout, transplanted to a river in Utah many years ago, is now being spawned at the hatchery.
As those fish grow, biologists will be able to ascertain if these “Pilot Peak” fish are in fact genetic throwbacks. If they are, some might eventually be released in Pyramid Lake to add to the genetic pool of these valuable breeding fish.
A”fingerling” is a fish up to one year of age and a “yearling” is the term used for the next year. After that, they’re just fish.
The Lahontan Fish Hatchery is located south of Gardnerville off Highway 395, on the Carson River. Hours are 8 a.m. to 3:30 p.m. Monday through Friday for guided tours. On weekends, you can go and view the fish on your own. For more information, call 265-2425.