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

Table 80. Multiple application scenarios for carbaryl and methomyl and predicted percent change
in lambdas for salmon populations
Carbaryl Methomyl
Crop examples
Almonds, chestnuts, pecans,
filberts, walnuts, pistachios
Sweet corn
Application rate 5 lbs a.i./acre 0.45 lbs a.i./acre
Number of
applications/yr
4 10
Application
interval
14 days 3 days
Method of
application
Aerial (fine-medium droplet
distribution)
aerial (fine-medium droplet distribution)
No-application
Buffer
none 100 ft
Off-channel water depth = 0.5 m
water depth = 0.5 m
habitat Initial average concentration Initial average concentration 8.55 μg/L;
characteristics 335 μg/L; 24 h exposure
96 h exposure
Ocean-type
Chinook
% change in Lambda
-19% -8%
Stream-type
Chinook
-15% -6%
Sockeye -16% -7%
Coho -18% -8%
Population­level consequences from other affected salmonid assessment endpoints and other
stressors of the action
In this section we present the population-level consequences from individual effects that are not
amenable to population modeling. In most cases we lack the empirical data to conduct
population modeling for these endpoints. Thus, we use qualitative methods to infer populationlevel
responses. We focus on the population metrics of abundance and productivity. Both are
metrics used by NMFS to assess a population’s viability and both can be compromised by the
chemicals assessed in this Opinion. Individual fitness consequences that reduce survival,
growth, reproduction, or migration can lead to reduced salmonid population viability if sufficient
numbers of individuals comprising a population are affected, and are more pronounced when
affected over multiple generations. If the reductions in fitness result in reducing a population’s
survival or recovery potential, then we consider whether the ESU or DPS is impacted (See
Integration and Synthesis section).
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