Editor's Note: This article by Ron Lee of Orem provides a good overview of the Strawberry Reservoir restoration project.
Discovery at Strawberry Reservoir of a thermocline, a heat induced layering of water, was the deciding factor in the decision to poison an overabundance of non-game fish species, according to biologists working on the project. The $2 million project is scheduled for October 1988, pending the completion of a study by the Environmental Protection Agency. Utah Division of Wildlife Resources biologist and Strawberry project leader Leo Lentsch, says the study is going well and should be completed by September 1987.
Some fishermen and biologists are concerned about the poisoning's effectiveness, cost, loss of trophy fish and renewal time.
Strawberry Reservoir is a huge body of water. It covers 1,106,000 acre feet and has a maximum depth of 240 feet, although most of the reservoir is between 20 and 80 feet deep. It is located east of Salt Lake City bordering the Uinta National Forest at an elevation of about 8,500 feet. The reservoir is about an hour and a half drive from Provo passing through Heber City. It is an extremely popular and important trout fishery.
A population explosion of non-game species has lowered the quality of fishing at the reservoir in recent years. Officials are now planning to poison the water and start anew. However, poisoning has never been attempted an a reservoir this size, putting the effectiveness in question.
Division of Wildlife Resources biologist Doug Sakaguchi explained the thermocline at Strawberry. He said late in the summer, the upper 30 feet of water is warmed much more than the lower layer. The difference becomes so great that the two layers cease to mix. Dead organic material in the lower layer is decomposed by bacteria. Bacteria uses oxygen in its composition. Since a body of water is oxygenated through its exposure to air at the surface, the layer below 30 feet is cut off from oxygen, making it unable to support fish. The fish all stay in the upper 30 feet of water. The thermocline thus greatly decreases the amount of water needed to be treated. "Instead of treating a 240-foot deep reservoir, in effect we have a 30-foot deep reservoir to treat," said Sakaguchi.
The reservoir will be treated with rotenone, a plant extract that inhibits the oxygen intake in fish. It breaks down rapidly and restocking will resume a few weeks after the treatment. Rotenone is nondiscriminating and will kill all forms of animal life in the water, including invertebrates which are the trout's food source. The biologists say that these invertebrates will quickly repopulate.
The culprits behind all of this is the Utah chub and Utah sucker, both non-game species commonly known as "trash" fish. They were probably introduced by fishermen who used the young minnows as bait and dumped the rest in after quitting. They are very prolific. One female chub can lay over 40,000 eggs each spawning season. They compete with trout for the same food.
Historically, Utah fishery managers have had success in treating waters with roterione. In 1961, Strawberry itself was poisoned to kill an overabundance of yellow perch. This was successful and until the 1980s Strawberry has been considered an excellent trout fishery.
"Strawberry is a unique cutthroat fishery," said Lentsch. "It can produce large cutthroats and large numbers of fish."
The reservoir is especially rich in nutrients that make insects and other invertebrates numerous. This abundance of food can produce a rapid rate of growth for the fish. "Unfortunately, the food is going to the chubs and suckers " said Al Mills, biologist from & U.S. Forest Service. As of late, sample nettings have resulted in only five trout for every 100 fish.
Three species of fish will be stocked in the reservoir after its treatment: Bear Lake cutthroat trout, kokanee salmon, and sterilized rainbow trout. The lake presently has cutthroat, rainbows, brook and a few brown trout.
The three fish species have been carefully chosen. Bear Lake cutthroat and kokanee were picked because their feeding habits will hinder chubs and suckers from re-establishing themselves in the reservoir.
The rainbow trout, which will be sterilized through heat-shock or chemical alteration of chromosomes, will provide a quick growing, catchable trout for the fishermen. The sterilization is necessary so their numbeirs can be controlled and so they don't interbreed with the native cutthroats.
Smallmouth bass have also been suggested in the future in case of trash fish troubles. They are very predacious and inhabit shallow waters where the chubs and suckers live.
Before 1985, there were two separate reservoirs next to each other: Strawberry and Soldier Creek. The dam on Strawberry was taken out and it was filled to Soldier Creek's level, flooding more land. The flooding has released an influx of nutrients which is helping the fish, but only temporarily, say biologists. In the two years previous to the dam removal, fish growth was very poor. DWR officials say the good fishing, due to the higher water levels, has confused anglers who wonder why the reservoir must be poisoned if fishing is hot. But the good fishing won't last, they say.
Small heads and football-shaped bodies were characteristic of the fast growing fish caught in the decade following the 1961 poisoning. Growth rates in trout should improve greatly following the poisoning, according to biologists. Trout planted now as 5-inch fingerlings are around 11 inches the next year, which is good, but temporary because of the floooding. It is hoped that after the treatment, trout will be 18 inches and about three pounds in two years. With improved growth rates, the DWR can plant smaller fish, thus saving money.
The reservoir is planned to be treated with rotenone at the end of October 1988. Within a few weeks, seven inch trout will be planted and fishing should resume in May of 1989.
One thing that will sadden many fishermen is the loss of the trophy fish now in the lake. It takes a long time to grow big fish. According to Charles Thompson, Division of Wildlife Resources biologist, the largest fish found in spawning traps since 1960 showed up this last year. "It was a beautiful 16-pound cutthroat, which shows that there are still nice trophy fish in the reservoir," he said.
Fred Mangum, U.S. Forest Service biologist, says loss of the trophy fish makes him a little indecisive about whether he favors poisoning the water. He said he remembers going up to Strawberry as a kid and catching lots of big trout. Although there aren't as many big trout as there once was, Mangum said the possibility of catching a trophy makes fishing at Strawberry interesting. "It might take 10, 12, 15 years to grow trout that big," he said in reference to growing 16-pound fish.
Marlin Harker, a Brigham Young University senior from Eugene, Oregon, is an avid fisherman who has done some research about the reservoir. Harker said he hates to see the trophy fish die. "The thing I like about Strawberry is that you don't know if the next fish will be 12 inches or 12 pounds," he said.
The state record cutthroat weighed 26 1/2 pounds and was caught in 1930 at Strawberry.
Another important part in the project to rebuild Strawberry is the restoration of 139 miles of spawning streams. Use of herbicides to increase pasture and grazing has degraded the streams so that trout cannot successfully reproduce. Rebuilding of banks, fencing and replanting of bank holding willows is planned for over 83 miles. It is hoped that the restoration will enable the trout to spawn and naturally restock. Goals of 10 million fingerlings are set for stream production.
Percentage of the rotenone kill is an important question. Biologists from the Division of Wildlife Resources think the kill will be about 99 percent. Fred Mangum doubts that it will be above 90 percent, taking into account the size of the reservoir and the many springs in it. Considering how the non-game species reproduce, this is a significant matter.
One exciting possibility of the poisoning is the prospect of having higher limits on the reservoir prior to the poisoning. Lentsch said limits likely won't be abolished entirely, but higher limits will probably be set in 1988 preceding the poisoning.
In November of 1986, after three years of deliberation, the Strawberry Interagency/Citizen Fisheries Advisory Team, composed of representatives from the Utah Division of Wildlife Resources, United States Forest Service, United States Fish and Wildlife Service, Bureau of Reclamation, Utah Wildlife Federation and Strawberry Bay Marina, developed a plan to restore the fishery at Strawberry. There may be great gains to be made but not without certain sacrifices. Hopefully Strawberry Reservoir will again be the great trout water it once was.
Copyright Dave Webb, 2005
