The South Fork Westslope Cutthroat Project, My Friend Leo, Part III

by Mike Peterson

There has always been a prevailing thought that Montana’s high mountain lakes should have fish. It’s kind of our heritage to hike or pack into wild and remote places, to camp and fish. These landscapes are rugged with short seasons, so fish did not proliferate in the mountain lakes naturally. Fish and Wildlife Biologists helped that part of the equation for us. Supplementing mountain lakes with fish began as some of Montana’s earliest wildlife projects dating back to the 1920’s. Programs to build fish hatcheries and stock mountain lakes became popular. One area that received a lot of attention was the Bob Marshall (not a designated wilderness until much later). Many of the mountain lakes were along the Swan range and into Jewell basin. Non-native fish were planted routinely in the lakes by horse and plane, creating headwater populations in areas that were historically fishless.

Picture of a classic Swan Lake. Maybe if you read this Mike will let you know where it is ???


Then, in the 1950’s, the Hungry Horse Dam was constructed. This isolated the entire South Fork of the Flathead River and all its lakes and drainages from the main Flathead River. However, there are 21 lakes that feed into the South Fork of the Flathead River. They had been stocked with yellowstone cutthroat, rainbow trout, and undesignated “cutthroat” for many years. In the late 1990’s fish scientists began to understand that these species represented a considerable threat to the native westslope cutthroat in the South Fork and restoration needed to be done.

In 2006 an Environmental Impact Statement on restoration of native fish to these lakes was completed and approved. From 2007 to 2017 the restoration of native fish to the 21 lakes was carried out. How the heck did they do it?? If I mention lakes like Doctor, Koessler, Lick, Lena, Blackfoot, Pyramid or Sunburst, you will quickly conjure up images of wild, remote places that are extremely hard to get to.

Enter my friend Leo and the FWP Fisheries Mitigation crew. (For 13 years Leo has been the Fisheries Manager for the Bob Marshall and Swan range.) This fisheries research program was created to mitigate for losses associated with the construction of Hungry Horse Dam. The project was led by biologists Matt Boyer and Sam Bourret, and required an “all hands on deck” approach to get the job done. The task became part of Leo’s job description as well.

Picture of Westslope Cutthroat being held in Danaher Creek waiting their ride out.


First, the 21 lakes had to be sterilized of the non-native fish. In six of the lakes, with good spawning habitat, and good westslope cutthroat populations, they used a technique called genetic swamping. They added so many pure westslope cutthroat to the lakes that they dilute the non-native fish genes in the population. In the other fifteen lakes this technique was not possible. This is when a biologist has to “lose part of his soul” and use chemicals to kill the fish present and sterilize the lakes. But, then the good part. The soul is restored by re-stocking the lakes with genetically pure cutthroat that will thrive in that environment.

So where do the fish come from? The FWP crew takes pack animals about 25 miles into the Bob Marshall Wilderness. Tributaries with high densities of juvenile genetically pure westslope cutthroats are used as donors for the project. Leo and his team will fly fish and catch/keep about 300 fish. They store them in the stream until they have enough and then pack them out by horses in oxygen rich fish containers. Leo assures me they do way better than any gold fish I have ever brought home from the store!!

Picture of FWP technician Gary Michael packing out 300 trout. 

They are put in a hatchery truck and taken to Sekokini Springs hatchery (the cutthroat day care center) and raised to maturity. Scott Relyea then works his magic as the hatchery manager. The fish are spawned and mixed to obtain genetic diversity (not all brothers and sisters). This method turns hundreds of fish into tens of thousands. They remain genetically pure westslope cutthroats. Currently, with genetic testing advancements, just a piece of fin can be given to the FWP geneticist (Ryan Kovach) at the University of Montana, and an entire DNA analysis is completed in short order. This gives those beautiful mountain lakes the fish with the best survival skills. A sustainable fishery that doesn’t have to be constantly restocked, allowing scarce finances to be spent elsewhere.

How do you pay for all of this? Remember the dam? When Hungry Horse was built, the dam flooded a lot of country and changed a lot of timber and water resources, including fish and wildlife. Bonneville Power Association (BPA) set up a mitigation fund to offset impacts associated with dam construction. This fund provides money each year that enables FWP to carry on these projects, and to restore and protect these area forever.

So, if you are ever lucky enough to stand on the shores of one of these incredible lakes, cast out a dry fly. If a beautiful westslope cutthroat rises to meet the challenge, think of my friend Leo and the great folks at FWP!!!

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