In western North America there are possibly five species of mussels commonly known as floaters. This page details the Yukon Floater (Sinanodonta beringiana) which was formerly in the genus Anodonta but reassigned to the genus Sinanodonta. It should be noted, however, that distinguishing between species of floaters in the west is problematic due in part to high variability in shape and physical characteristics between individuals. Information in this page is specific to the Yukon floater when available.
The Yukon floater is known to occur in Oregon, Alaska, and the Yukon Territory. Yukon floaters can be found in lakes and streams in sand and gravel stream bottoms. The species attains a maximum length of about eight inches.
Yukon floaters are most often found in sand and gravel bottoms of lakes and streams within its range.
A considerable inland body of standing water.
A natural body of running water.
Like all freshwater mussels, Yukon floaters are filter feeders that siphon suspended particles from the water column. They may consume plankton, bacteria, dissolved organic matter, or algae. This filtering provides an important water quality service by reducing turbidity and controlling nutrient levels, especially where there are dense mussel beds. Particles not used by the mussel are often re-formed and expelled as larger particles that are in turn used as food by other aquatic life.
Freshwater mussels are sedentary organisms, spending their entire lives near where they settled. They can use their foot to move laterally across sediments (usually short distances) or vertically within the sediments. Mussel movements may be related to reproduction or a response to physical disturbance and environmental changes such as water temperature, stream flows, or scouring of the stream bed. Mussel displacement due to high flows or dislodgement due to predators or human activity also likely occurs. The main mode of mussel dispersal comes through a stage of development when larvae (glochidia) parasitize a host fish and move with the host within the aquatic system.
The Yukon floater has a maximum length of about eight inches and is elliptical or elongate. The shell length is typically double that of the shell height. There are no wings on the dorsal posterior portion of the valves. Yukon floaters are olive-green during the juvenile life stage and changes to nearly black in older individuals. The interior color of the shell ranges from gray to dull blue. No teeth are present on either valve.
Anodonta species become sexually mature at about four to five years of age and can live up to about 15 years. Relative to other western mussel species, they are considered to be short lived and fast growing. Male mussels release sperm into the water column and a female takes it in through her incurrent siphon to fertilize eggs. Fertilized eggs migrate within the mussel to a special portion of the gill known as the marsupium. The eggs develop into larvae called glochidia and are released by the female in the spring through early summer. Once released the glochidia, which look like very tiny mussels, attach to a host fish’s gills where they become encysted and remain for weeks to months until they detach and settle to the substrate. Mussel species are often specific regarding what species of fish they use as hosts. The Yukon floater is known to use sockeye salmon (Onchorynchus nerka), Chinook salmon (Onchorynchus tshawytscha) and three-spined stickleback (Gaserosteus aculeatus) as host species. Timing of reproductive events is affected by habitat, water temperature and the individual host species.