Native fish populations in Glacier National Park have been severely compromised by the invasion and expansion of non-native fish species into the park’s lakes and streams. Non-native fish can affect native fish populations through predation, hybridization, and competition and are imperiling populations of bull trout, which are federally listed as threatened, and the native westslope cutthroat trout, a state listed Species of Concern. Of the seventeen lakes on the west side of the park that support bull trout, nine have been compromised by non-native lake trout and a tenth has been compromised by the non-native brook trout.
Quartz Lake, located in the North Fork of the Flathead River drainage and the park’s North Fork District, is one of the last remaining strongholds for bull trout in park waters west of the Continental Divide. Until recently, Quartz Lake was believed to be the largest lake on the west side of the park accessible to lake trout but not yet colonized by them. In 2005, lake trout were detected in Quartz Lake, threatening the long-term persistence of the Quartz Lake bull trout population. At that time, a fish passage barrier designed to protect the drainage from invasion by non-native fish was under construction on Quartz Creek, approximately 100 yards below Middle Quartz Lake, but completion of the barrier was suspended until options to control lake trout could be reviewed. The National Park Service has since collaborated with the U.S. Geological Survey and others in an ongoing experimental program to remove lake trout from Quartz Lake to suppress the population. Experimental suppression has so far been promising, with identification of lake trout spawning areas and annual removal of spawning lake trout. Data suggests that the project is successfully removing a high percentage of spawning adults annually, which is expected to eventually reduce the lake trout population over time.
The NPS is proposing to complete, modify, and improve the existing Quartz Creek fish barrier. The purpose of the project is to support lake trout suppression efforts in Quartz Lake, reduce the potential for additional lake trout to enter the lake, and reduce the likelihood of invasion from other non-native species such as rainbow trout and brook trout, thereby better protecting the integrity of native fish populations in the upper Quartz drainage.
According to the environmental assessment, the park is proposing to raise the barrier's total height by 1-2 feet in order to prevent further migration of lake trout into Quartz Lake. The EA calls for installing about 28 gabions (wire mesh cages filled with rock, each two feet high, two feet wide and six feet long) on and near the existing barrier.
If you would like to comment on this proposal, please click here. The comment period ends on 3/19/2012.
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