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

Data on population abundance and trends are limited for the California portion of this
ESU. No regular estimates of natural spawner escapement are available. Historical point
estimates of coho salmon abundance for the early 1960s and mid-1980s suggest that
statewide coho spawning escapement in the 1940s ranged between 200,000 and 500,000
fish. Numbers declined to about 100,000 fish by the mid-1960s with about 43%
originating from this ESU. Brown et al. (1994) estimated that the California portion of
this ESU was represented by about 7,000 wild and naturalized coho salmon (Good,
Waples et al. 2005). In the Klamath River, the estimated escapement has dropped from
approximately 15,400 in the mid-1960s to about 3,000 in the mid-1980s, and more
recently to about 2,000 (Good, Waples et al. 2005). The second largest producing river
in this ESU, the Eel River, dropped from 14,000, to 4,000 to about 2,000 during the same
period. Historical estimates are considered “best guesses” made using a combination of
limited catch statistics, hatchery records, and the personal observations of biologists and
managers.
Most recently, Williams et al. (2006) described the structure of historic populations of
SONCC coho salmon. They described three categories of populations: functionally
independent populations, potentially independent populations, and dependent
populations. Functionally independent populations are populations capable of existing in
isolation with a minimal risk of extinction. Potentially independent populations are
similar but rely on some interchange with adjacent populations to maintain a low
probability of extinction. Dependent populations have a high risk of extinction in
isolation over a 100-year timeframe and rely on exchange of individuals from adjacent
populations to maintain themselves.
Critical Habitat
Critical habitat was designated for the SONCC coho salmon on November 25, 1997, and
re-designated on May 5, 1999. Species critical habitat encompasses all accessible river
reaches between Cape Blanco, Oregon, and Punta Gorda, California and consists of the
water, substrate, and river reaches (including off-channel habitats) in specified areas.
Accessible reaches are those within the historical range of the ESU that can still be
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