Salmonids are a family of fish that are born in freshwater streams, live most of their life in the ocean, then return to the same stream to spawn and die.  Because each stream has its own set of specific environmental conditions, populations of salmon, even within a species, are specially evolved for a their birth stream's special conditions.  This degree of specialization has made salmonids extremely sensitive to change, and many salmonid populations are consequently in decline.

Forage Fish are not glamorous, but constitute a critical element in an estuarine ecosystem.  These are fish at the base of the food chain, providing nutrients for a broad spectrum of birds and mammals, as well as for other, larger fish species.  At Nisqually, the most common forage fish include stickleback, shiner, perch, sand lance, salmonids and herring.