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

The Status of Listed Resources and Environmental Baseline sections indicate that fisheries,
timber harvest, vineyards and other agriculture, non-native fish species, and migration barriers
negatively affect this ESU. Adverse effects on Chinook salmon habitat include a high
percentage of fines in the streams’ bottom substrate, lack of large instream woody debris,
reduced riparian vegetation, elevated water temperatures, degraded water quality, increased
predation, and barriers that limit access to tributaries. The combined impacts from these multiple
threats continue to affect the CC Chinook salmon. Accumulation of fine sediment in the bottom
substrate, contamination of waters, lack of riparian vegetation, and non-natives fish species are
expected to impact invertebrate abundance and composition in streams within the ESU.
Most of the agriculture and urban developments are concentrated in the Russian River valley and
on alluvial plains of coastal rivers. Vineyards and smaller centers are dispersed along coastal
watersheds. Based on the crop types, we expect carbaryl and methomyl are commonly applied
throughout the growing season in the Russian River basin. We also expect use of the a.i.s on the
alluvial plain of the lower Eel River and its estuary, and to a lesser extent along the lower
portions and estuaries of other coastal streams. Carbaryl is expected to be used the entire year
within urban/residential areas. Existing stocks of carbofuran are also expected to be applied
throughout the growing season. In California, there are 61 pesticides that inhibit AChE approved
for use and we expect that application of other AChE inhibiting pesticides will co-occur with the
a.i.s, exacerbating adverse effects from AChE inhibition. However, monitoring data for
pesticides in streams within the CC Chinook salmon ESU is lacking. Adults within Willapa Bay
during 24(c) carbaryl application to oyster beds are likely exposed to this compound and may
experience additional mortalities.
CC Chinook spawning occurs on gravel beds in the mainstem of rivers and larger tributaries.
Fry use the floodplain, stream margins, and side channels to rear after emergence from the redds
in December through mid-April. Downstream migration of juveniles starts as early as February
and most enter marine waters before mid-summer.
We expect the proposed uses of carbaryl and carbofuran pesticide products that contaminate
aquatic habitats will lead to individual fitness level consequences and subsequent population-
437