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

protected channel features. The off-channel floodplain habitats provide feeding and growth
opportunities that are important before smoltification and seaward migration in the spring. The
presence of discrete brood years (BYs) makes coho salmon more vulnerable to environmental
perturbations than other salmonids because a failed BY is unlikely to be replaced by other BYs.
Land use data indicate substantial overlap between high-use areas and fish runs in the Russian
River, San Francisco Bay, and the Santa Cruz area. In several streams, one or more BYs are at
the verge of extinction, and heavy pesticide exposure may result in the loss of a BY. We expect
the proposed use of the three carbamates will lead to both individual fitness level consequences
and subsequent population-level consequences. Therefore, the risk to this species’ survival and
recovery from the proposed action is high for carbaryl, carbofuran, and methomyl.
Lower Columbia River Coho Salmon
The LCR coho salmon ESU includes all naturally spawned coho salmon populations in streams
and tributaries to the Columbia River in Washington and Oregon from the mouth of the
Columbia up to and including the White Salmon and Hood rivers, and along the Willamette to
Willamette Falls, Oregon. The ESU includes 26 historical populations and 25 artificial
propagation programs. Over 90% of the historic populations of LCR coho salmon are
considered extirpated. Most populations have very low numbers and have been replaced by
hatchery production. Only two populations have a degree of natural spawning – the Sandy River
and the Clackamas River. The annual population growth rates known for the Sandy River and
Clackamas River are 1.102 and 1.028, respectively.
The major threats to LCR coho salmon identified in the Status of Listed Resources and
Environmental Baseline sections include reduced water flow in the mainstem and estuary from
irrigation diversions and hydroelectric dams. Additionally, degraded water quality in freshwater
and tributary habitats negatively affects this ESU. Among the various types of habitat threats,
elevated temperature, water diversions, and poor water quality have significant influence on the
status of LCR coho salmon.
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