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

Reduction in Prey
Freshwater spawning, rearing, and migratory habitats must provide forage areas that support
juvenile development. A reduction in the abundance of prey items will decrease the
conservation value of these habitats, as they will support fewer individuals, especially during a
salmonid’s first year of survival. Given the environmental baseline conditions of the aquatic
systems, the existing invertebrate community is already depauperate in many of these areas and
requires longer periods for recovery following each pesticide application event. The a.i.s in
surface runoff and pesticide drift entering freshwater rearing habitats will exacerbate reductions
in insect communities that are salmonid prey items in these degraded systems. We expect that
designated critical habitats that support juvenile feeding and growth will be contaminated by the
proposed uses of carbaryl, carbofuran, and methomyl to the extent that the habitat is precluded
from serving its intended role in the survival and recovery of listed salmonids. The overall
conservation value of designated critical habitat, whether low, medium, or high, will not meet its
intended role to support the survival and recovery of the species.
Reduction in Water Quality
Drift and runoff from areas of intensive urban and agricultural development will likely contain
carbaryl, carbofuran, and methomyl in addition to other pesticides - particularly other AChEinhibiting
pesticides, chemical pollutants, and sediments that also degrade water quality.
Depending on the available water flow, amount of shade from LWD and intact riparian zones,
and water temperature in aquatic habitats, the toxicity of carbaryl, carbofuran, and methomyl in
tributary and stream waters may become more pronounced. Reductions in water quality may
reduce the conservation value of designated habitats used for spawning, rearing, and migration.
Furthermore restoration actions promoted in many of the salmonid recovery plans focus on
increasing flood plain connectivity and creating new off-channel habitats. These actions are
proposed in agricultural and urban flood plains that overlap with uses of the three insecticides.
Water quality (as well as prey availability) may be degraded in these newly constructed habitats
from the stressors of the action- effectively precluding intended benefits to rearing juvenile
salmonids. We expect that proposed uses may contaminate these areas, thereby precluding
habitat from its intended purpose in supporting the survival and recovery of listed Pacific
salmonids.
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