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Montana Mussel Poster Now Available

June 30, 2010


(HELENA) - The Montana Natural Heritage Program is pleased to announce the release of the "Mussels of Montana" poster. This poster summarizes available knowledge of freshwater mussels in Montana from the last three years of surveys and data collection.

Dave Stagliano, the Aquatic Ecologist at NHP, is the project leader. Stagliano, and a team of other field biologists and zoologists, have spent the last several years conducting hundreds of surveys and numerous workshops across the state to bring attention to these overlooked invertebrates, which are sometimes incorrectly referred to as clams.

"Mussels are a seldom seen and underappreciated biological component of many Montana trout streams and prairie rivers," said Stagliano. "Few people even know that Montana's waterways are the native home to several mussel species; most press goes to the exotic zebra mussel."

These cryptic organisms, which closely resemble rocks on a river bottom, are vital to the health of Montana's waterways. Mussels have an amazing filtering capacity and are able to filter eight gallons of water every four hours, keeping Montana's streams and rivers clean. Large numbers of mussels are of great benefit to waterways that have silt or nutrient problems because of their filtering capacity.

Additionally, mussels have host relationships with fish that are important to Montana's streams and rivers, including the westslope cutthroat trout, sauger, and catfish. If fish populations are low, the number of mussels in Montana's waterways declines, which can result in dirtier waterways. For example, Montana's only trout stream mussel, the western pearlshell, has been disappearing from watersheds for decades following the westslope cutthroat trout decline. Prior to mining and dams, the Clark Fork River had abundant populations of this species. Now instead of showing up in Montana waterways, the western pearlshell shows up on Montana's Species of Concern list.

"The presence of these long-lived mussel species is indicative of a watershed's past, current, and future health," said Stagliano. "That's why studying mussel populations throughout Montana and providing workshops on these organisms is such important work."

This project was funded and supported by the Montana Fish Wildlife & Parks State Wildlife Grants (MT FWP SWG) program and the Montana Natural Heritage Program (NHP). Additional assistance was provided by Dan Gustafson of Montana State University who contributed valuable data, photographs and discussion to the research project.

Montanans can pick up their free "Mussels of Montana Poster" at the MT FWP Headquarters Lobby, FWP Regional Offices, or at the Montana State Library.

The Montana Natural Heritage Program provides information on Montana's species and habitats, emphasizing those of conservation concern. The Program is operated by the University of Montana in partnership with the Montana State Library. For more information on Montana's mussel species and the Montana mussel poster, contact Dave Stagliano at (406) 444-7329 or by email at


View a PDF of the Poster

Sara J. Groves
Marketing and Communications Coordinator
Montana State Library
PO Box 201800
Helena, MT 59620-1800
PH: (406) 444-5357