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

consequences and subsequent population-level consequences. The uses of these materials in
some natal areas and along migratory routes may cause acute lethality, temporary AChE
inhibition, and reduced growth. We expect that exposure to methomyl may lead to individual
fitness consequences, but not to an extent that would affect population growth rates. The risk to
SR steelhead survival and recovery from the stressors of the action is high for carbaryl and
carbofuran, but low for methomyl.
South­Central California Coast Steelhead
The S-CCC steelhead DPS includes all naturally spawned steelhead in streams from the Pajaro
River to the Santa Maria River. The major basins in the S-CCC steelhead range are the Pajaro
River system and the Salinas River system. Carmel River, a smaller basin, also supports a stable
run of steelhead. Historic abundance estimates for the DPS imply an annual return may have
been upwards of 20,000 fish. The estimated production in five of the major rivers indicates a
return of less than 500 adults.
The major threats to this DPS identified in the Status of Listed Resources and Environmental
Baseline sections are dams and other migration barriers, urbanization and channel modification,
agricultural activities, and wildfires. These activities has resulted in reduced channel
complexity, eroded banks, increased water temperature, migration barriers restricting access to
cooler head waters, and decreased water quality from contaminants.
About 7% of the DPS is developed for cultivation of crops; a large portion of this land is in the
Salinas River valley. Crops are concentrated in low laying areas and floodplains along the
estuaries and lower reaches of streams. Based on the crop types, we expect carbaryl, carbofuran,
and methomyl are commonly applied within the DPS throughout the growing season.
Approximately 8% of the DPS has been developed for urban and residential purposes.
Developed areas are located at the mouth of several streams within the S-CCC steelhead DPS.
We expect carbaryl use in urban/residential areas throughout the entire year.
All S-CCC steelhead are a winter-run life history. Juvenile steelhead remain in freshwater for
one or more years before migrating downstream to smolt. Steelhead in this area consists of two
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