GREEN RIVER — Anglers fishing at Flaming Gorge Reservoir should expect reduced kokanee salmon catch rates in 2023 compared to previous years.
Fisheries managers from the Wyoming Game and Fish Department and Utah Division of Wildlife Resources set a management objective to maintain a population estimate of 600,000 kokanee two years and younger. Estimates in 2021 and 2022 were 600,000 and 550,000, respectively.
Estimates from 2016-2019 were nearly double the most recent estimates. Kokanee population recruitment estimates show a decline of over 50 percent when comparing estimates from 2021-2022 to estimates from 2016-2019.
Managers are concerned the decline is a result of predation by small (<28 inches) lake trout. Recently completed research concluded that the diet of small lake trout consisted of roughly 25 percent kokanee. A large population of small lake trout can easily overwhelm kokanee recruitment. For example, suppose the population of small lake trout is around 130,000 small lake trout, each consuming just 10 kokanee yearly. That equates to 1.3 million kokanee being lost to predation and unavailable to anglers in the future.
Each fall, fisheries managers operate a fish trap in Sheep Creek to collect early and late-run eggs from spawning kokanee. Utah managers could not meet their egg quota for early runs in 2022, and Wyoming managers could not collect any eggs in 2022 due to the absence of late run kokanee. As a result, the number of kokanee stocked in Flaming Gorge by Utah will be reduced.
Wyoming Game and Fish will be able to meet its stocking quota because of the kokanee brood held at the Tillett Springs Rearing Station, which can meet statewide kokanee stocking requests. The Jones Hole National Fish Hatchery will also be a few hundred thousand kokanee, as they’ve done in previous years. Overall, between the three agencies, the number of kokanee stocked this year will nearly meet the stocking objective of 1.65 million kokanee.
To mitigate lake trout predation on kokanee, anglers are encouraged to target small lake trout and take advantage of liberal creel limits. In January 2019, the creel limit for small (<28 inches) lake trout was increased to 12 per day and 24 in possession, with only one trout greater than 28 inches allowed. Small lake trout are healthy to consume, low in mercury and high in omega 3s.
Trout and kokanee stocking began May 16 and will continue around the reservoir at major boat ramps through the middle of June.
“It is a great time to target small lake trout around the structures associated with the boat ramps where fish are being stocked to reduce predation,” Green River Fisheries Biologist John Walrath said. “The majority of the stocking activity will occur at the Buckboard and Brinegar’s Ferry boat ramps, the best time to catch lake trout is early morning.”
Through early to mid-June, lake trout will be in the shallows while shoreline water temperatures are cool. They will push to deeper, cooler water once shoreline temperatures warm up. Harvesting more small lake trout will increase the number of rainbows, cutthroat, and kokanee available to anglers.
For tips on how to catch and cook small lake trout visit the Flaming Gorge Management page.