What are anadromous fish?

Tomorrow is World Fish Migration Day (WFMD). The ancient migration story of fish ascending rivers from oceans to breed is miraculous.  Such fish – called anadromous, from the Greek word  “anadramein” meaning “running upward” – include salmon, steelhead, shad, sturgeon, lamprey in the Pacific Northwest; and shad, sturgeon, alewives and herring along the US East Coast.

USA:  Washington, Columbia River Basin, Ilwaco mural of salmon
USA: Washington, Columbia River Basin, Ilwaco mural of salmon

Anadromous fish swim from the sea inland via open rivers to spawn in small headwater tributaries. In so doing, they bring with them marine nutrients that enrich riverine flora, fauna and forests.  After their long journeys back to where they were born, the adult fish release their eggs in cool, forested waters and then die.  Thus, some hail anadromous fish as the greatest parents of all, because the nutrients of their remains nourish the flies and insects that are eaten by newly-hatched smolt.

This month, our NWNL Snake River Expedition is documenting the dynamics of anadromous fish in the Pacific Northwest and the studies of local fish biologists, fishermen, watershed managers and the Nez Perce tribal nation.  Today, NWNL joins them and the world in honoring the ecosystem services and sustenance values provided by anadromous fish.

Canada:  British Columbia, Winlaw, Slocan River Valley, salmon mural
Canada: British Columbia, Winlaw, Slocan River Valley, salmon mural

*Check out 10 (very interesting!) Things You Might Not Know About Migratory Fish.

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