Freshwater Mussels Pacific Northwest - The Xerces Society

unknown. Native hosts with which mussels have coevolved might be superior
to nonnative hosts because their populations may be more stable in the
long-term. Also, the mussel may be specifically adapted to traits unique to its
native host, such as habitat use, behavior, and lack of immune responses to
glochidial parasitism 5 .
M. falcata has been extirpated throughout much of the mainstem Snake
River and Columbia River of Oregon and Washington 13,30 and has dramatically
declined in abundance in one area of the Truckee River of California 111 .
This species historically existed in northern Utah, but has probably been extirpated
from the state 76 . The range of M. falcata is also contracting in Montana;
historical populations from some larger rivers such as the Blackfoot, Big
Hole, Bitterroot, and Clark Fork have been extirpated from the entire drainage,
or are only present in low numbers 90 . Many historic sites have been lost
and some populations show little evidence of recruitment 41,52 . The fate of this
species throughout much of its native range remains uncertain.
Freshwater Mussels of the Pacific Northwest 35