For the watersheds of the Pacific Northwest, dead salmon -- rotting, stinky, gross -- provide crucial nutrients to support diverse, complex freshwater environments.

Pacific salmon complete almost all of their growth while living in the ocean. When they migrate back to natal streams and die, decomposition releases calcium, phosphorous and nitrogen into the water, enriching streams with nutrients that feed algae, aquatic insects and juvenile salmon.

The salmon goodness spreads to plants and wildlife. Studies of some old confer trees growing near rivers have revealed marine nitrogen isotopes that could only have come from rotting salmon.

But recent declining salmon runs have raised concerns about the health of watersheds as they lose those nutrients. Researchers believe that nutrient deficiencies -- because of fewer decomposing salmon -- actually hinder the recovery of salmon and steelhead populations.

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