Even a modest reduction in first year mortality, on
the order of 10%, during juvenile residence in either the river or
the estuary ecosystem, can mitigate current population declines
of Snake River spring/summer Chinook salmon in the Columbia
River Basin of North America (Kareiva et al., 2000). Therefore even
a small reduction in disease resistance due to chemical exposure
can potentially have a significant impact on salmonid population
health.