Authors : Alexa Maine, Clay Arango and Christine O'Brien
Freshwater mussels play an important role in stream ecosystems but are declining worldwide. The California floater (Anodonta californiensis, Lea 1852), formerly widespread throughout the Pacific Northwest, is listed as a federal species of concern and a candidate species for state listing in Washington (WA). Because freshwater mussels are obligate parasites on fish, conservation and restoration efforts require understanding specific host fish species. We found a previously undocumented population of A. californiensis in the upper Yakima River Basin in WA and determined its host fishes through a combination of laboratory and field studies. Two fish species, speckled dace (Rhinichthys osculus) and torrent sculpin (Cottus rhotheus), were confirmed as hosts for A. californiensis. Two fish species, three-spine stickleback (Gasterosteus aculeatus) and redside shiner (Richardsonius balteatus), were identified as hosts for A. californiensis in the laboratory portion of this study. Our results fill a significant data gap for building a successful conservation and restoration program by extending the known range of A. californiensis within the Yakima River Basin, and by identifying a suite of suitable host fishes for A. californiensis, including two that had not been previously confirmed as hosts. Our results can be incorporated into a management approach that focuses on the conservation and recovery of not only A. californiensis, but its host fishes as well.