DECEMBER 13, 2019

Wyoming Game and Fish Works to Reduce Numbers of Small Lake Trout in Flaming Gorge

Lake trout less than 28 inches in Flaming Gorge Reservoir are very abundant. They are the highest ever documented, and anglers are catching them frequently while targeting other species. But, their high-numbers are taxing their own food supply resulting in slower growth during the years lake trout should be growing quickly. If a population becomes too large for their environment, growth rates decrease and prey resources become limited. The current lake trout regulation on the Wyoming side of the reservoir is 12 fish per day and 24 in possession, with only one greater than 28 inches. The more liberal regulation went into effect January 2019 to encourage anglers to take advantage of this robust population and help reduce the abundance of small lake trout in the reservoir.

Prior to the 1990s, there were fewer young lake trout (< 7 years of age) and lots of Utah chub, crayfish and zooplankton to eat. Lake trout grew quickly and helped sustain the trophy fishery. By the 1990s, the reservoir matured and Utah chub became less abundant, meaning there were more mouths to feed but fewer groceries to feed them. Now as a result, the juvenile and young adult lake trout are growing slower and the chances of them reaching trophy size is diminishing. Additionally, if their population exceeds the capacity of their environment, they could negatively impact their prey populations - kokanee.

Although the introduction of burbot did not cause the lake trout problem, burbot are exasperating it by competing with the small lake trout for important prey items such as crayfish and small-bodied prey fish.

Angler harvest is the best management tool we have to reduce the numbers of small lake trout. This is a great time of year to pursue small lake trout because they are more accessible through the ice if you do not own a boat and are especially tasty this time of year.

pictured: John Walrath
Green River Fisheries Biologist