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

limited to a very restricted portion of the historical range. Significant spawning occurs in
only two of the 16 historical populations. Nearly 88% of the historical populations are
extirpated. The two remaining populations are the Grays River and the Lower Gorge
(Good, Waples et al. 2005). Chum salmon appear to be extirpated from the Oregon
portion of this ESU. In 2000, the Oregon Department of Fish and Wildlife (ODFW)
conducted surveys to determine the abundance and distribution of chum salmon in the
Columbia River. Of 30 sites surveyed, only one chum salmon was observed.
Historically, the Columbia River chum salmon supported a large commercial fishery in
the first half of this century which landed more than 500,000 fish per year as recently as
1942. Commercial catches declined beginning in the mid-1950s, and in later years rarely
exceeded 2,000 per year. During the 1980s and 1990s, the combined abundance of
natural spawners for the Lower Gorge, Washougal, and Grays River populations was
below 4,000 adults. In 2002, however, the abundance of natural spawners exhibited a
substantial increase at several locations (estimate of natural spawners is approximately
20,000 adults). The cause of this dramatic increase in abundance is unknown.
Estimates of abundance and trends are available only for the Grays River and Lower
Gorge populations. The 10-year trend was negative for the Grays River population and
just over 1.0 for the Lower Gorge. The Upper Gorge population, and all four of the
populations on the Oregon side of the river in the Coastal MPG, are extirpated or nearly
so (McElhaney, Chilcote et al. 2007). However, long- and short-term productivity trends
for populations are at or below replacement. Regarding spatial structure, few Columbia
River chum salmon have been observed in tributaries between The Dalles and Bonneville
dams. Surveys of the White Salmon River in 2002 found one male and one female
carcass and the latter had not spawned (Ehlke and Keller 2003). Chum salmon were not
observed in any of the upper gorge tributaries, including the White Salmon River, during
the 2003 and 2004 spawning ground surveys. Finally, most Columbia River chum
populations have been functionally extirpated or are presently at very low abundance
levels. The loss of off-channel habitat and the extirpation of approximately 17 historical
populations increase this species’ vulnerability to environmental variability and
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