You can obviously use a computer to write here...use it to do five minutes worth of reasearch.
OK.
This is for Keith and his interest in the lower Columbia, like Abernathy Creek or Germany Creek.
http://www.nwcouncil.org/fw/program/2008amend/spe/history.pdfSalmon Life Histories, Habitats, and Food Webs in the
Columbia River Estuary
Daniel J. Bottom
NOAA Fisheries, NW Fisheries Science Center
2032 SE Marine Science Drive, Newport, OR 97365
Ph: 541/867-0309 Fax: 541/867-0389
dan.bottom@noaa.gov
Throughout the past century, two competing assumptions have directed management efforts in
the Columbia River estuary on behalf of salmon: (1) the estuary is irrelevant to conservation
because fresh water conditions limit salmon production; and (2) the estuary is a threat to juvenile
salmon because bird and mammal predators are concentrated in the narrow lower-river corridor.
These ideas have ignored the estuary’s role as a productive nursery ground and transitional
habitat for salmon stocks throughout the Columbia River Basin. The Columbia River estuary
contributes to salmon life history diversity by providing habitat opportunities for juveniles with
subyearling-migrant life histories. Small subyearling Chinook salmon seek shallow water rearing
habitats and occupy a diversity of emergent, shrub, and forested wetlands throughout the tidal
freshwater and brackish areas of the Columbia River estuary. Many estuarine-rearing juveniles
feed in wetland channels, grow on average 0.5 mm per day, and reside in the estuary for weeks
or months before entering the ocean. Recent estuarine surveys suggest that life history diversity
among subyearling Chinook salmon has declined since early in the twentieth century and could
limit the resilience of contemporary populations to changing environmental conditions.
Numerous changes upriver (e.g., hatchery programs, population losses, flow regulation) and
within the estuary (e.g. wetland habitat losses, increased water temperatures) may have
contributed to the apparent reduction in life history variation. Loss of tidal wetlands could further
limit the capacity of estuarine food webs to support juvenile salmon. Energy flow to salmon is
derived from wetland detritus, and juveniles throughout the estuary feed on insect prey that is
produced in wetland habitats. Although sources of wetland detritus have declined during the last
century, contemporary salmon food webs still rely disproportionately on wetland-derived prey.
All Columbia Basin ESUs are represented in estuarine habitats, and a diversity of genetic stock
groups, including interior summer/fall stocks, rear in tidal wetland habitats of all types. Recovery
of Columbia River salmon will require that sufficient habitat opportunity is provided in the
estuary to accommodate the full complement of stocks and life history types in the basin. Among
the principal concerns in the estuary for salmon recovery programs are loss of peripheral wetland
and tidal floodplain habitats; effects of hatchery programs and flow regulation on patterns of
estuarine migration, residency, and habitat use; and the risk of increasing water temperatures on
summer and fall rearing opportunities for young salmon.
References Columbia River Estuary
Anderson, G. O. 2006. Variations in estuarine life history diversity of juvenile Chinook salmon
based on stable isotope analysis of food web linkages. M.S. Thesis. School of Aquatic
and Fisheries Sciences, University of Washington, Seattle, WA.
Bottom, D. L., and K. K. Jones. 1990. Species composition, distribution, and invertebrate prey of
fish assemblages in the Columbia River estuary. Progress in Oceanography 25:243-27
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