Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Chinook salmon are dependent on the quantity and quality of aquatic habitats. Juvenile
salmonids rely on a variety of non-main channel habitats that are critical to rearing. All
listed salmonids use shallow, low flow habitats at some point in their life cycle.
Examples of off-channel habitat include alcoves, channel edge sloughs, overflow
channels, backwaters, terrace tributaries, off-channel dredge ponds, and braids (Anderson
1999; Swift III 1979). Chinook salmon, like the other salmon NMFS has listed, have
declined under the combined effects of overharvests in fisheries; competition from fish
raised in hatcheries and native and non-native exotic species; dams that block their
migrations and alter river hydrology; gravel mining that impedes their migration and
alters the hydrogeomorphology of the rivers and streams that support juveniles; water
diversions that deplete water levels in rivers and streams; destruction or degradation of
riparian habitat that increase water temperatures in rivers and streams sufficient to reduce
the survival of juvenile Chinook salmon; and land use practices (logging, agriculture,
urbanization) that destroy or alter wetland and riparian ecosystems. These activities and
features introduce sediment, nutrients, biocides, metals, and other pollutants into surface
and ground water and degrade water quality in the freshwater, estuarine, and coastal
ecosystems throughout the Pacific Northwest.
Salmonids along the west coast of the U.S. share common threats. Therefore,
anthropogenic threats for all species and stocks are summarized here (see (NMFS 2005)
for a review). Population declines have resulted from several human-mediated causes.
However, the greatest negative influence has been the establishment of waterway
obstructions such as dams, power plants, and sluiceways for hydropower, agriculture,
flood control, and water storage. These structures have blocked salmon migration to
spawning habitat or resulted in direct mortality and have eliminated entire salmon runs.
Presently, many of these structures have been re-engineered, renovated, or removed to
allow for surviving runs to access former habitat. However, success has been limited.
Remaining freshwater habitats are threatened from development along waterways as well
as sedimentation, pollution run-off, habitat modification, and erosion. These factors can
directly cause mortality, affect salmonid health, or modify spawning habitat so as to
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