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

period, habitat improvements included the removal of several small dams and increases
in summer flows in the watersheds, a reduced ocean fisheries, and a favorable terrestrial
and marine climate. All three spring-run Chinook populations in the Sacramento River
tributaries have long-and short-term lambdas >1, indicating population growth.
However, population sizes are relatively small compared to fall-run Chinook salmon
populations, and there have been some extreme fluctuations in population size, which is
often indicative of an impending collapse in small populations. Additionally, Feather
River hatchery and Feather River spring-run Chinook salmon are not closely related to
the Mill, Deer, and Butte creek spring-run Chinook salmon populations. This group
represents a distinct genetic legacy. Although protective measures and critical habitat
restoration likely have contributed to recent increases in spring-run Chinook salmon
abundance, the ESU is still below levels observed from the 1960s through 1990. Threats
from hatchery production (i.e., competition for food between naturally spawned and
hatchery fish, and run hybridization and homogenization), climatic variation, reduced
stream flow, high water temperatures, predation, and large scale unscreened water
diversions persist.
Critical Habitat
Critical habitat was designated for this species on September 2, 2005 (70 FR 52630).
The critical habitat designation for this ESU identifies PCEs that include sites necessary
to support one or more Chinook salmon life stages. Specific sites include freshwater
spawning sites, freshwater rearing sites, freshwater migration corridors, nearshore marine
habitat, and estuarine areas. The physical or biological features that characterize these
sites include water quality and quantity, natural cover, forage, adequate passage
conditions, and floodplain connectivity. Factors contributing to the downward trends in
this ESU include: loss of most historical spawning habitat, reduced access to
spawning/rearing habitat behind impassable dams, climatic variation, water management
activities, hybridization with fall-run Chinook salmon, predation, and harvest. Additional
factors include the degradation and modification of remaining rearing and migration
habitats in the natal stream, the Sacramento River, and the Sacramento delta. The natal
tributaries have many small hydropower dams and water diversions that in some years
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