Distribution Across the CTUIR Ceded Areas
Locations where freshwater mussels were present (colored markers) and absent (black markers) during CTUIR FWMRRP surveys in CTUIR ceded areas. Note: The presence of Margaritifera falcata in the upper Umatilla was an outplanting test site and not a surviving population.
Explore Mussel Distribution by Basin
Instream Habitat
All three genera (Anodonta, Gonidea, and Margaritifera) are found in a variety of sediment types. The main factor associated with preferred mussel habitat is non-eroding, consolidated substrate. River substrates that are stable during high-water events may be the best indicator of good mussel habitat. Freshwater mussel beds generally occur in areas where the shear stress is lowest during high-water events. In addition to their preference for non-eroding stream bed sediments, freshwater mussels also require the presence of suitable host fishes. Features considered unsuitable for freshwater mussel habitat include: bedrock, easily erodible stream bed sediments, boulders and cobbles that lack interstitial fines, and stream segments with a slope greater than 3%. Freshwater mussel habitat preferences and requirements are not well understood, and development of habitat suitability models for these organisms is underway.
Western Pearlshell in sand and gravel mix.
The California Floater and Western Ridged Mussel are at home in consolidated sand
California Floater and Western Pearlshell hanging out in a cobble gravel mix.
