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

UCR Spring-run Chinook salmon begin returning from the ocean in the early spring. After
migration, they hold in freshwater tributaries until spawning in mid- to late August. Fish spawn
in the major tributaries leading to the Columbia River between Rock Island and Chief Joseph
dams. UCR Spring-run Chinook salmon fry typically select offchannel
habitats associated with their natal rivers and streams to rear. Juveniles spend a year in
freshwater before migrating to the ocean in the spring of their second year of life. The duration
of juvenile rearing in shallow freshwater habitats increases their susceptibility to higher
exposures of pesticides, contaminants, and elevated temperature.
Given the life history of UCR Spring-run Chinook salmon, we expect the proposed uses of
carbaryl, carbofuran, and methomyl pesticide products that contaminate aquatic habitats will lead
to individual fitness and subsequent population-level consequences, i.e., reductions in population
viability. Therefore, the risk to this species’ survival and recovery from the stressors of the
action is high for carbaryl, carbofuran, and methomyl.
Puget Sound Chinook Salmon
The Puget Sound ESU includes all runs of Chinook salmon in the Puget Sound region from the
North Fork Nooksack River to the Elwha River on the Olympic Peninsula. This includes 31
historic quasi-independent populations and 26 artificial propagations programs. Of the historic
populations, only 22 are considered extant. The estimated total run size for this ESU in the early
1990s was 240,000 fish. During a recent five-year period, the geometric mean of natural
spawners in populations of this ESU ranged from 222 to just over 9,489 fish (Good, Waples et
al. 2005). Recent five-year and long-term productivity trends remain below replacement for the
majority of the 22 extant populations of Puget Sound Chinook salmon. The annual population
growth rate known for these populations ranged from 0.75 to 1.17.
The major threats to the Puget Sound Chinook salmon identified in the Status of Listed
Resources and Environmental Baseline sections include degraded freshwater and marine habitat
from agricultural activities and urbanization. Poor forestry practices have also reduced water
quality in the upper river tributaries for this ESU. Elevated temperature, water diversions, and
poor water quality across land use categories pose significant threats to the status of Puget Sound
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