Rare fish found in 2 lakes in Northwest Montana
KALISPELL – Fisheries biologists have made a startling discovery in a pair of northwestern Montana lakes, and information sheds light on the distribution of a rare native fish species.
Montana Fish, Wildlife and Parks biologists Sam Bourret and James Deraleau, along with National Science Foundation intern Niall Clancy, embarked on a research project to better understand the distribution of the pygmy whitefish, a small salmonid referred to as special concern in Montana. These unique fish are very different from their cousins of the mountain whitefish and lake whitefish, as they live and spawn in deep lakes. They arrived when Glacial Lake Missoula was formed by glaciers about 10,000 to 20,000 years ago. When the large lake retreated with the glaciers, these deeper lakes were left with the right conditions for the survival of the pygmy whitefish.
Kalispell-based FWP biologists have started looking for these elusive fish over the past year as part of the agency’s regular management and monitoring efforts. The nets have been placed deeper than normal in an attempt to find pygmy whitefish, and two lakes have emerged successfully so far: Tally Lake near Whitefish and Big Salmon Lake in the Bob Marshall Wilderness.
“It is exciting that we are still making scientific discoveries about the distribution of pygmy whitefish in northwestern Montana,” said Bourret.
The discovery is helping biologists gain new data on this centuries-old species that will help inform the FWP of its distribution, predator impacts and habitat requirements. Since the distribution of Pygmy Whitefish is associated with glacial refugia and the fact that they are mostly found under 100 feet in cold water lakes, it is likely that they are sensitive to warming temperatures.
Another important reason to learn more about the pygmy whitefish is the role it plays in the ecosystem’s overall food web. Although found in a limited number of water bodies, pygmy whitefish can serve as an important food source for other fish, such as bull trout and lake trout, and even for birds. A comprehensive study of the feeding habits of fish from Flathead Lake and the lower Flathead River in 1981 showed that Pygmy Whitefish made up at least 58% of Bull Trout’s dietary biomass in October and November.
“It is important to study the pygmy whitefish because all aspects of the food web impact the entire native fish assemblage,” said Bourret. “By better understanding the pygmy whitefish, we are better equipped to conserve and manage aquatic ecosystems in the face of the impacts of climate change.”
Pygmy whitefish are known as ‘broadcast spawners’ – meaning they typically spawn during periods of mass spawning for one or more consecutive months – in shallows and tributaries of lakes, but the specific physical characteristics of spawning sites are not well described. They migrate over short distances. In late November and December, they leave Flathead Lake and congregate at the mouths of the Swan and Flathead rivers before entering the river systems to spawn. They have been identified in Bull, Horseshoe, Little Bitterroot, Ashley, Whitefish, McDonald, Hungry Horse, Lindbergh, Holland, Ross Creek, Flathead, and Ashley Creek lakes.
The state record pygmy whitefish – 9.84 inches long and 0.36 pounds in weight – was captured on February 13, 2010 by Richard Geldrich at Little Bitterroot Lake, near Marion.