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

hatchery fish in naturally-spawning steelhead populations. During this review NMFS
was unable to identify any natural populations that would be considered at low risk.
All populations declined from 1980 to 2000, with sharp declines beginning in 1995.
Historical counts in some of the larger tributaries (Cowlitz, Kalama, and Sandy Rivers)
suggest the population probably exceeded 20,000 fish. During the 1990s, fish abundance
dropped to 1,000 to 2,000 fish. Recent abundance estimates of natural-origin spawners
range from completely extirpated for some populations above impassable barriers to over
700 for the Kalama and Sandy winter-run populations. A number of the populations have
a substantial fraction of hatchery-origin spawners in spawning areas. These populations
are hypothesized to be sustained largely by hatchery production. Exceptions are the
Kalama, the Toutle, and East Fork Lewis winter-run populations. These populations
have relatively low recent mean abundance estimates with the largest being the Kalama
(geometric mean of 728 spawners).
According to Good et al. (2005), most populations are at relatively low abundance.
Those with adequate data for modeling are estimated to have a relatively high extinction
probability. Some populations, particularly summer run, have shown higher return in the
last two to three years. Many of the long-and short-term trends in abundance of
individual populations are negative, some severely so. The trend in natural spawners is