Teton river trout

A study conducted last summer revealed largely good news for the area’s native cutthroat trout population. The Teton River (pictured above) is home to increasingly robust populations of Yellowstone Cutthroat Trout.

During the summer of 2020, the Friends of the Teton River conducted an assessment of native trout populations across the Teton River watershed. The fisheries staff and volunteers visited 56 pre-established research sites on tributaries flowing from the Teton Mountain Range. Repeated every five years, the goal of this study is to monitor changes in trout populations in the region, and measure the effectiveness of efforts to improve the fishery.

The teams utilized a variety of methods to analyze the spawning habitat and strongholds for native Yellowstone Cutthroat Trout. These native currently occupy less than half of their historic range (43%), and less than a quarter of them remain genetically unaltered (23%).

Max Lewis, the Friends of the Teton River’s Fisheries Crew Lead, joined Mike Lien, the organization’s Stream Restoration Director, in a virtual presentation last week that presented the study’s results. Many of the team’s discoveries were hopeful and spelled good news for native trout. However, a few trends indicated that further work is needed to ensure the future of native Yellowstone Cutthroat.

“The analysis of the data collected over the past 15 years shows that there is a marginally-significant decreasing trend in total trout abundance of 2% per year,” observed Lewis. “Despite a decline in total abundance, there are no changes in the Yellowstone Cutthroat Trout species composition signaling that Yellowstone Cutthroat Trout continue to do well in the watershed.”

Bitch, Badger, and Darby Creeks revealed high numbers of healthy cutthroat. Their upper waters are clear and clean, and do not have any infiltration by nonnative species like brook or brown trout.

Trail, North Leigh, Game, Fox Creeks all currently have high numbers of Eastern Brook Trout, which are invasive and compete with cutthroat. However, the study noted that native cutthroat populations are still hanging on and show some hope of rebounding with continued protection and restoration efforts.

The main part of the Teton River has demonstrated hopeful trends as well. The study did note that while the numbers of cutthroat in the stretch between Packsaddle and Harrop’s—known as the Breckenridge Reach—cutthroat are increasing from a historically low number, but the section has also seen a significant increase in the number of brown trout. The trend is concerning, note the fishery experts.

Mike Lien noted that in coming years, there may be efforts by the Idaho Fish & Game to remove or significantly reduce the number of brown and brook trout in the area in order to active bolster the cutthroat population — an effort that the Friends of the Teton River would support enthusiastically.

The presentation also summarized the variety of restoration and conservation projects undertaken by the group over the past years and noted that there has been a clear correlation between those projects and the increase in cutthroat trout. Efforts like fish ladders, screens, and riverbank restoration have improved the quality of the waters as well as the habitat for native fish.

Ultimately, it looks like a good angling season is on the horizon, said the team. They observed that there will likely be a lower overall flow in the watershed this year due to a thin snowpack and lack of late season precipitation. This means that runoff is likely to peak two to three weeks earlier than last year, and clear conditions will arrive earlier, too. Late season, they warn, could see some warm water temperatures that can stress fish — so the quality of late season fishing remains to be seen.

The presentation is available online via the Friends of the Teton River channel on YouTube.