Biologists from the Utah Division of Wildlife Resources are delighted with their success so far in eliminating fish from Strawberry Reservoir.
The final round of rotenone treatments, this time focusing on tributaries to the great reservoir, begin Monday and will last 20 days. The South American chemical is being used to eliminate chubs and other non-game species from Strawberry and its contributing streams."In all of our monitoring after the treatment we haven't found any fish yet," Leo Lentsch, the division's Strawberry Project leader, told a scientific seminar Thursday afternoon. The meeting of the Utah Non-Point Pollution Source Water Quality Conference continues Friday at the Yarrow Hotel here.
Monitors checking the reservoir and tributaries after the first treatments - which started in July - found that rotenone levels are correct, he said.
"This fall we're restocking the Bear Lake cutthroat and sterile rainbows," two trout species, he said. About 700,000 of the new fish will be 7 inches long, and 600,000 will be 3 inches.
Depending on the success of rehabilitating the streams so that they are more productive for trout, Lentsch said, Strawberry Reservoir could become self-sustaining around 1996-98. Meanwhile, fishing can resume on Jan. 1, 1991, he told the session.
"Everything looks really good," he said in a Deseret News interview after his talk. "All of our (rotenone) concentrations were right where they needed to be, and the gill netting hasn't shown any fish yet."
When the chemical seeped throughout the reservoir, wiping out all the fish, the division found that about 99 percent were non-game species. It also killed the zooplankton, microscopic animals that form an important part of the aquatic food chain, as rotenone inhibits animals' ability to absorb oxygen.
The zooplankton may be rebounding already. In another week or two it could be so common that the division starts restocking with trout.
To help improve the tributaries, the U.S. Forest Service recently banned cattle from the area for five years. Stream banks will be stabilized by planting junipers to control erosion, which can dump sediment into the channels.
"We're going to try to maximize some spawning channels," by putting in special gravel that the trout use for spawning, he said.
Asked what the ice fishing will be like at Strawberry on Jan. 1, he said, "There'll be some small fish."
How long will it take before the fishing is really good? "I would say that in '93 you'll see it getting close to its potential and start to regain its Western reputation as a major cutthroat fishery."