Montana may not be the first place one associates with salmon, a fish famous for its epic ocean migration. Despite its distance from the Pacific coast, salmon do swim in the state’s deep, cold waters. These populations are a unique biological exception to the typical salmon life history.
The salmon found in Montana are landlocked populations, not the ocean-going fish familiar to coastal regions. They complete their entire life cycle exclusively within freshwater lakes and reservoirs. Their presence results from historical stocking efforts or the isolation of native populations behind massive hydroelectric dams. This distinct freshwater environment allows Pacific salmon species to survive without ever reaching saltwater.
The Most Common Montana Salmon: Kokanee
The most successful and widespread salmon in Montana is the Kokanee, the landlocked form of the Sockeye salmon (Oncorhynchus nerka). Genetically identical to their ocean-migrating cousins, Kokanee spend their entire lives within large freshwater bodies, substituting the sea. The species was first introduced to Flathead Lake in 1914. It is now established in many cold, deep reservoirs across the western half of the state, including Lake Koocanusa.
Kokanee are primarily filter-feeders, subsisting almost entirely on zooplankton, which are tiny aquatic crustaceans. This diet influences their size, which is typically around one pound, though some individuals reach three to five pounds. The abundance of plankton, such as Daphnia, determines the overall health and size of a Kokanee population.
The life cycle of the Kokanee typically spans four years, culminating in a spawning event in the fall. Prior to spawning, the fish undergo a striking physical transformation. Their typically silver bodies turn bright red, and males develop a pronounced humped back and a hooked jaw, or kype.
Mature fish migrate up tributary streams or move to shallow lake shorelines to build their nests, known as redds. Like all Pacific salmon, adult Kokanee die shortly after spawning, providing a seasonal source of nutrients for local wildlife. Their ability to naturally reproduce in many Montana waters makes them a stable and self-sustaining landlocked fishery.
Other Stocked Pacific Salmon Species
While Kokanee are the most numerous, Chinook salmon (Oncorhynchus tshawytscha) are stocked in Montana to provide a large, trophy sport fish option. The most notable population is found in Fort Peck Reservoir, where they were first introduced in 1983. This stocking effort utilized the reservoir’s immense size and deep, cold water to mimic a marine environment.
These Chinook are highly predatory, feeding on other pelagic fish in the reservoir, primarily cisco and goldeye. The success and size of the Chinook population are directly tied to the availability of cisco, which serves as their primary forage base. Chinook in Fort Peck can grow to impressive sizes, with some individuals exceeding 25 pounds, and the state record stands at over 32 pounds.
The Chinook population in Montana is not self-sustaining and requires continuous intervention from fisheries managers. Since these fish cannot reproduce naturally in the reservoir, state agencies annually collect eggs from mature salmon to raise fingerlings in hatcheries. The annual stocking goal at Fort Peck is to release a minimum of 200,000 fingerlings to maintain the sport fishery.
Past attempts to establish other Pacific salmon species, such as Coho salmon, have been less successful or are no longer actively pursued. Chinook stocking efforts in other areas, like the Missouri River above Canyon Ferry Reservoir in the early 1970s, were discontinued after yielding only smaller fish. The Chinook program at Fort Peck represents the state’s primary effort to manage a large, non-reproducing salmon species.
The Landlocked Life Cycle
The landlocked status of Montana’s salmon is a direct consequence of massive hydrological engineering across the Pacific Northwest. Traditional Pacific salmon are anadromous, meaning they hatch in freshwater, mature in the ocean, and return to their natal streams to spawn and die. The Columbia River system, which drains much of western Montana, was historically the migratory route for these fish.
The construction of large dams without fish passage facilities permanently blocked access to the upper reaches of the Columbia River Basin. Dams like Grand Coulee (1941) and Chief Joseph Dam (1961) created an impassable barrier that ended the upriver migration of anadromous salmon into Montana. This blockage isolated over 40% of the historic spawning and rearing habitat in the Columbia River Basin.
Salmon species that survived above these barriers, or were later introduced, adapted to a purely freshwater existence. Deep, cold reservoirs and large natural lakes effectively replaced the ocean environment. The salmon utilize the deep, cold, open-water zone, known as the limnetic zone, for feeding and growth, mirroring their oceanic counterparts. This adaptation allows them to complete their entire life cycle without the physiological shift necessary for saltwater survival.