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and the USGS began an experimental project on Quartz Lake, located in the park’s remote northwest corner, where lake trout invasion was still in its early stages of invasion. The aim was to reduce or eliminating lake trout by gillnetting, a project that required a boat to be heli- coptered in and all of the supplies to be hauled in by biologists and mules.
Clint Muhlfeld, aquatic ecologist for the USGS Northern Rocky Mountains Science Center, and his team rst located so-called “Judas sh,” captured and radio-tagged them, then tracked the sh to spawning areas in order to capture and remove the most dense concentrations of spawning lake trout.
In seven years, the project has shown evidence of success in reducing lake trout, and is hailed as one of the rst suc- cessful projects of its kind and a leading example that lake trout suppression, once thought to be futile, is possible.
Now, biologists with both agencies have received approval to continue the federal program on Quartz, and have applied a similar method of lake trout removal to Logging Lake, which was once among the most robust bull trout sher- ies in the park, but is now on the cusp of blinking out due to lake trout invasion.
A second element to the Logging Lake project involves translocation of bull trout—the rst of its kind in the upper Columbia basin—where biologists moved 107 bull trout from Logging Lake to a safe haven called Grace Lake, an upstream body of water that is protected from lake trout invasion by a waterfall, which serves as a natural barrier.
“We captured as many of the remain- ing bull trout in Logging Lake as possible and literally put them on our backs in a bucket, hiked up a trail and released them in Grace Lake,” Muhlfeld said. “Now we’ll focus our e orts on suppressing that Lake Trout population in Logging.”
Meanwhile, a team of researchers led by Muhlfeld recently completed the park’s rst comprehensive genetic assess- ment of westslope cutthroat trout inside the park’s boundaries, giving park man- agers a genetic inventory and providing baseline genetic status and distribution information that can be used for priori- tizing management e orts to protect and restore the genetic integrity of westslope cutthroat trout populations in Glacier Park.
For the past ve years, Muhlfeld and his team have scoured the park’s three river basins that are historic ranges to native westslope cutthroat—the Colum- bia, Missouri and South Saskatchewan— dispatching an army of y- shers into the park’s remote corners to cull genetic samples.
“My crew will probably tell you it was the coolest summer job they’ve ever had,” Muhlfeld said.
Of the 115 populations sampled in the three river basins, 34 contained hybrid samples, while 36 conservation popula- tions were identi ed, 19 of which were
tagged as having medium-low to medi- um-high risk of hybridization. Twelve populations were at high risk of hybrid- ization, while ve populations were at low risk, all of them located upstream of sh passage barriers.
Biologists like Muhlfeld have been tracking the reproductive success of hybridized trout, and recent evidence suggests they aren’t doing well.
“The hybrid o spring have greatly reduced tness and a diminished ability to produce o spring and have those o - spring survive,” he said.
In 2014, Muhlfeld led a project study that linked the rapid hybridization between native Montana trout species and invasive species in the Flathead River system to climate change.
In the past three decades, hybridiza- tion between native westslope cutthroat trout and invasive rainbow trout has rapidly accelerated in the Flathead River
system, a range-wide stronghold, accord- ing to a groundbreaking study.
Although the threat from introduced rainbow trout was held at bay for decades, climate change gave rise to accelerated hybridization.
“So essentially, hybridization was a time bomb waiting to go o under the right environmental conditions,” Muhl- Ofeld said.
N A RECENT SUMMER MORN-
ing in East Glacier, Muhlfeld
humped a Ghostbusters-like elec- tro shing backpack along a tributary of Glacier National Park’s Two Medicine River drainage, stunning cutthroat in order to gather genetic samples.
The tributary is one of only two streams in the Missouri River drainage that con- tains a conservation population of genet- ically pure westslope cutthroat, and park managers hope to maintain its integrity.
According to Downs, the genetic assessment will help park managers prioritize conservation actions as they develop their sh management plan.
“It’s going to help us identify where we want to conduct conservation actions and further research, with the intent of being able to secure populations rst and fore- most, as well as restore populations that have been extirpated,” Downs said.
“Part of the sh management plan will be identifying potential projects that would bene t native sh including west- slope cutthroat, and the success of the South Fork Lakes project is a pretty good model for what can be done to make some large scale gains for westslope cutthroat. I think we have similar opportunities in the park.”
Boyer said while most native trout res- toration projects rely on continued sup- pression, the South Fork project is unique in that there is a nish line.
“Suppression is an ongoing e ort. It’s mowing the lawn. Here you are able to remove the threat, introduce a self-sus- taining, genetically pure population and get out,” Boyer said. “That is the beauty of this project. There is a nish line.”
tscott@ atheadbeacon.com
“IT’S KIND
OF LIKE THE ARK,
AND IF WE DO OUR JOB REALLY WELL, THIS PRECLUDES THE NEED TO LIST THE SPECIES UNDER THE ENDANGERED SPECIES ACT.”
- BRIAN MAROTZ, FWP
Clint Muhlfeld, a Flathead-based aquatic ecologist with the U.S. Geological Survey in Glacier National Park, shows a section of a n from a cutthroat trout to test its DNA as he conducts research along Midvale Creek. GREG LINDSTROM | FLATHEAD BEACON
JULY 6, 2016 // FLATHEADBEACON.COM
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