NANFA-- salmon nutrients

Jay DeLong (
Fri, 18 Feb 2000 09:59:50 -0800

The Fisheries article on the nutrient deficit is:
Ted Gresh, Jim Lichatowich and Peter Schoonmaker. 2000. An Estimation of
Historic and Current Levels of Salmon Production in the Northeast Pacific
Ecosystem: Evidence of a Nutrient Deficit in the Freshwater Systems of the
Pacific Northwest. Fisheries 25(1):15-21.

The researchers used historical cannery records and present escapement and
harvest data to determine biomass and marine-derived nitrogen and
phosphorous delivered by adult salmon to streams in WA, OR, ID and CA. They
estimated annual historic biomass to 160-226 million kg, and present levels
to be 11.8-13.7 million kg. This means just 6-7% of historical
marine-derived nutrients are presently being made available to plants and
animals of freshwater and terrestrial ecosystems. They authors suggest this
is both a symptom and a cause of ecosystem failure.

Analysis of bone samples from the skeletons of grizzly bears killed in the
Columbia Basin between 1856 and 1931 show 31-91% of carbon and nitrogen were
derived from marine nutrients. The article lists several more examples of
animals dependent upon salmon carcasses: minks which alter mating behavior
to coincide with the availability of carcasses for their young to eat,
dependence of young salmon on the nutrients released by their decomposing
parents, aquatic plant and algae growth, and more. And these nutrients are
distributed far upstream into the watershed in the bodies of the animals
that feed on the salmon.

Jay DeLong
Olympia, WA

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