Kokanee Salmon in Strawberry Reservoir

By Ron Stewart, DWR NE Region

When Strawberry Reservoir was treated to remove Utah chubs and suckers, biologists wanted to restock the reservoir with fish that could either "out compete" chubs for food or prey on chubs to keep them from becoming a problem in the future. One of the first fish the biologists looked at was the kokanee salmon.

Kokanee feed on zooplankton, small microscopic animals that float with the currents in lakes and rivers. Even as kokanee grow, they retain their ability to feed on the smaller zooplank on which make them an excellent competitor against other fish that utilize zooplankton as their major food source. Besides being an excellent competitor, kokanee are highly prized by anglers for their fight and tasty table qualities. As a result, the fisheries biologists felt kokanee could be a vital part of the Strawberry fishery.

Once the biologists decided on kokanee, they needed to find egg sources. As Strawberry is a large reservoir, they wanted to stock it with 1.25 million kokanee each year. After checking with several sources, they realized the kokanee eggs would have to be taken from Utah sources as most of the out of state sources were diseased and not acceptable. At the time of the decision, only the Sheep Creek run from Flaming Gorge was certified as disease-free. Biologists started a disease certification process at Porcupine Reservoir to add another source. This was completed in 1990, the same year Strawberry was treated.

Fortunately, the number of fish spawning in Sheep Creek exceeds the stream's spawning habitat. Sheep Creek is a small stream and there are too many spawning females for the space available in the gravel beds. Late spawners dig their reads, or nests, on top of the reads of earlier spawners. This dislodges, or covers the eggs already in the gravel and can actually decrease the productivity of the stream. But, it offers a window of opportunity. Eggs from the surplus, or redundant spawners can be taken without fear of hurting the Flaming Gorge fishery, especially since almost all of the Flaming Gorge kokanee spawn on the shale inside the reservoir.

Unsually kokanee choose streams in which to spawn but biologists working Flaming Gorge have found the three biggest runs of kokanee never leave the reservoir.

The biologists know almost all of the kokanee there utilize broken, loose shale deposites as gravel and they believe the winds, pushing waves into a steep bank, have created an aerated downward current much like a mountain stream.

Similar studies showed the inlet on Porcupine also had redundant spawners so traps were set there as well.

The hatcheries now had two sources of fish to rear but as the rune are small, Strawberry Reservoir has received only a quarter of the fish requested. Fortunately, the kokanee planted into the reservoir in 1991 didn't wait the usual four years to mature. An estimated 1,900 started a run at Indian Creek in 1992, and a few found other smaller tributaries. An even greater number cruised the banks of the Soldier Creek area looking for a stream to spawn in. This placed the runs at Strawberry a couple years ahead of schedule. Eventually, Strawberry will replace Sheep Creek as the major source of kokanee eggs in Utah.