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

system and consequently affect swimming ability of fish. Behavioral modifications, such
as changes in swimming performance, are regularly considered in NMFS’ Opinions.
Swimming performance therefore is an assessment endpoint. Measurable changes in
swimming speed are the assessment measure used to evaluate this endpoint. Reductions
in swimming performance could also affect other assessment endpoints such as migration
and predator avoidance. We may or may not have empirical data that address these
endpoints, resulting in a recognized data gap. This uncertainty would be identified
during the problem formulation phase, and discussed in the risk characterization phase.
Critical Habitat Risk Hypotheses:
To determine potential effects to designated critical habitat, NMFS evaluates the effects
of the action by first looking at the effects on PCEs of critical habitat. Effects to PCEs
include changes to the functional condition of salmonid habitat caused by the action in
the action area. Properly functioning salmonid PCEs are important to the conservation of
the ESU/DPS. The stressors of the action for this Opinion are chemicals. As such, the
key PCEs that are potentially affected are salmonid prey availability and degradation of
water quality in freshwater spawning sites, freshwater rearing sites, freshwater migration
corridors, estuarine areas, and nearshore marine areas. We developed two risk
hypotheses based on these PCEs:
1. Exposure to the stressors of the action is sufficient to reduce abundance of aquatic
prey items of salmonids; and
2. Exposure to the stressors of the action is sufficient to degrade water quality in
designated critical habitat.
These hypotheses are evaluated using the best scientific and commercial data available
presented in the Response section. Examples of assessment endpoints evaluated include
prey survival, prey growth, prey drift, prey reproduction, abundance of prey, health of
invertebrate aquatic communities, recovery of aquatic communities following pesticide
exposure, etc. If the available evidence supports the risk hypotheses, then NMFS
evaluates whether the potential reductions in PCEs are localized or widespread. The
potential reduction of PCEs affect on the conservation value of designated critical
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