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

(number of
listed
ESUs)
Steelhead
(11)
General life histories of Pacific salmonids (continued)
Spawning Migration Spawning Habitat Juvenile Rearing and Migration
Mature adults (three to
five years old) may enter
rivers any month of the
year, and spawn in late
winter or spring.
Migration in the Columbia
River system extends up
to 900 miles from the
ocean in the Snake River.
Steelhead are iteroparous
(can spawn more than
once).
Usually spawn in
fine gravel in a
riffle above a pool.
276
The alevin life stage primarily
resides just below the gravel
surface until they approach or
reach the fry stage. Immediately
after leaving the gravel, swim-up
fry usually inhabit shallow water
along banks of stream or aquatic
habitats on streams margins.
Steelhead rear in a wide variety
of freshwater habitats, generally
for two to three years, but up to
six or seven years is possible.
They smolt and migrate to sea in
the spring.
Modeling: Estimates of Exposure to Carbaryl, Carbofuran, and Methomyl
Exposure estimates for non­crop pesticide applications
EPA’s BEs indicate that pesticides containing carbaryl, carbofuran, and methomyl are
registered for over 100 use sites (EPA 2003; EPA 2003; EPA 2004). As previously
indicated, many of the uses identified in the BEs have since been modified, or are
scheduled to be phased out or cancelled. The BEs provided relatively few estimates of
exposure given the number and variety of uses authorized (Table 48). All modeled
exposure estimates assumed pesticide use in agricultural crops. No estimates were
provided for other uses of carbaryl, carbofuran, or methomyl.