The IDF&G Southeast Region office manages Daniels, Springfield, Treasureton and Twenty-Four Mile Reservoirs to be trophy rainbow trout fisheries (no bait, barbless hooks, two fish limit, none under 20”). Studies for each have determined size, weight and population estimates for rainbow in each. This information helps fly fishers decide which reservoirs are most interesting to try for trophy rainbows. Treasureton is the reservoir we look at today. See below.
Rainbow trout as well as rainbow trout x cutthroat trout hybrids, commonly called hybrids, were captured at Treasureton Reservoir in the 2023 survey. Twenty-seven rainbow trout were sampled with an average length of 18 inches and average weight of 2.5 pounds. These averages have increased since the 2017 electrofishing survey when rainbow trout averaged 15.8 inches and 1.7 pounds. The largest rainbow trout captured in 2023 was 25.6 inches and weighed 5.75 pounds.
Our survey also captured 21 hybrids with an average length of 16 inches and average weight of 1.8 pounds. The average size of hybrids has decreased since 2017 when average length was 19.8 inches and weight was 2.8 pounds. The largest hybrid captured in 2023 was 21.8 inches and weighed 4.3 pounds. Harvestable trout were more numerous in Treasureton Reservoir than Daniels Reservoir with 27% of the sampled trout measuring 20 inches in length or greater.
Treasureton Reservoir was treated with rotenone in 2018 to eliminate largemouth bass. Our survey did not capture any largemouth bass, which is good news for the trout fishery. Treasureton Reservoir also has an additional regulation with no size or bag limit on bass species to help prevent their establishment. However, we did capture 363 green sunfish with an average size of 4.8 inches. This species was likely illegally introduced sometime after the 2018 rotenone treatment. Fisheries managers will be watching this population closely to determine if it may negatively impact the trophy trout population in Treasureton Reservoir.
