WALL CREEK – Teams of workers and volunteers from Montana Fish, Widlife and Parks, the Forest Service and the Madison River Foundation spent last Thursday and Friday wading up Ruby Creek south of Ennis to help with a conservation project to remove rainbow trout from the stream and make room for a genetically pure population of westslope cutthroat trout.
The crews used electronic equipment to shock the fish in the stream so they could be netted.
The shocking equipment runs a current through the water that temporarily stuns fish. The fish float to the surface of the water where they are easily collected with a net. The teams of state agency employees and volunteers collected dozens of rainbow trout this way, placing them unharmed in live wells anchored in the creek. Once the live wells were full, the trout were transferred to a water truck from the Ennis fish hatchery to transport them to the Madison River.
The key to the project, said FWP fisheries biologist Pat Clancey, is a 15-foot high waterfall located near the bottom of the tributary. The series of boulders and trapped debris act as a natural barrier that prevents rainbow trout from the Madison River moving upstream into Ruby Creek.
Clancey explained that native populations of westslope cutthroat trout have been diminished down to 3 to 5 percent of their historic range, largely due to the introduction of rainbow, brook and brown trout. Rainbow trout hybridize with cutthroat trout. Brown and brook trout out compete the cutthroats for food. All three species will essentially displace native westslope cutthroat populations given the opportunity.
“Each individual population has a somewhat unique genetic makeup, different from other westslope cutthroat populations even in an adjacent drainage,” Clancey said. “We’re trying to expand and combine populations to kind of revitalize genetic makeup.”
Once crews have removed as many rainbow trout as possible using electroshock equipment, they will return later this fall and use a rotenone treatment to kill off any remaining fish before a genetically pure population of cutthroat trout is established in Ruby Creek.
“The cutthroat trout that we want to establish in this drainage are the last two aboriginal Madison drainage cutthroat trout populations,” Clancey
explained. “This stream, once we’re done, will have eight or nine miles of habitat available for cutthroat trout.”
If the live wells full of colorful rainbows splashing about under the thick canopy of brush and vegetation covering Ruby Creek are any indication, the project will be an important step forward in preserving and protecting the native species.
“Just judging from what we’ve seen in here so far this year with rainbow trout, we should have a really healthy cutthroat trout population in here when we’re done,” Clancey said.