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

lambda values of the nine existing populations range from 0.85 to 1.39 (Good, Waples et al.
2005). The Hood Canal Summer-run chum salmon populations are the subject of an intense
hatchery program intended to bolster numbers. As much as 60% of the spawning populations are
hatchery-raised fish.
The major threat to this ESU identified in the Status of Listed Resources and Environmental
Baseline sections is habitat degradation. The combined effects of degraded floodplains,
estuarine, and riparian habitats, along with reduced stream flow and sedimentation, have had a
profound negative impact on this ESU.
The land use and environmental data indicate that the Hood Canal Summer-run chum may be
exposed to carbaryl, carbofuran, and methomyl. There is no cultivated crop land and less than
6% of the ESU is developed. Washington’s 24(c) registrations for carbofuran use are not
expected to be employed in this region. We do expect some exposure due to residential uses.
The Hood Canal Summer-run chum spawn from mid-September through mid-October (Tynan
1997). Emergence generally occurs from early February through mid April. Upon emerging, fry
immediately commence downstream migration to estuaries (Tynan 1997). Upon arrival in the
estuary, salmon fry inhabit nearshore areas in shallow water. In Puget Sound, they have been
observed to reside in the top 6 inches of surface water and extremely close to the shoreline
(Tynan 1997). This behavior increases the likelihood of acute exposure to drift and runoff events.
Given the life history of the Hood Canal Summer-run chum, we expect the proposed uses of
carbofuran, carbaryl, and methomyl pesticide products may contaminate aquatic habitats and
lead to individual fitness level consequences. We expect that exposure will occur, resulting in
lethality and sublethal olfactory-mediated effects. We do not, however, expect that these effects
will have population-level consequences. As chum fry are more precocious and quickly leave
natal streams, they are less reliant on the local invertebrate population. Therefore, risk to this
species’ survival and recovery from the stressors of the action is low for carbaryl, carbofuran,
and methomyl.
452