Mitigating Impacts of Natural Hazards on Fishery Ecosystems

<em>Poster Abstract</em>.—Beginning in the late 1990s, agencies in the greater Seattle area began conducting fall surveys for spawning salmon to evaluate the effectiveness of local stream restoration efforts. These surveys detected a surprisingly high rate of mortality among migratory coho salmon <em>Oncorhynchus kisutch </em>females that were in good physical condition but had not yet spawned. In addition, adult coho from several different streams showed a similar progression of symptoms (disorientation, lethargy, loss of equilibrium, gaping, fin splaying) that rapidly led to death. In recent years, prespawn mortality (PSM) has been observed in many lowland urban streams, with overall rates ranging from ~25% to 90% of the fall runs.