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

Overall abundance for SR fall-run Chinook salmon is relatively low, but has been
increasing in the last decade (Good, Waples et al. 2005). The 1997 to 2001 geometric
mean natural-origin count over Lower Granite Dam approximate 35% of the proposed
delisting abundance criteria of 2,500 natural spawners averaged over 8 years. The recent
abundance is approaching the delisting criteria. However, hatchery fish are faring better
than wild fish.
Regarding productivity [population growth rate (lambda)], the long-term trend in total
returns is >1; indicating the population size is growing. Although total abundance has
dropped sharply in the past two years, it still remains at levels higher than previous
decades. Productivity is likely sustained largely by a system of small artificial rearing
facilities in the Lower SR Basin. The growth trend for natural-origin fish is close to 1,
and could either be higher or lower, depending on the number of hatchery fish that spawn
naturally.
The historic spatial structure has been reduced to one single remnant population. The
ESU occupies a relatively small amount of marginal habitat, with the vast majority of
historic habitat inaccessible. Genetic diversity is likely reduced from historic levels.
Hatcheries affect ESU genetics due to three major components: natural-origin fish
(which may be progeny of hatchery fish), returns of SR fall-run fish from the Lyons Ferry
Hatchery program, and strays from hatchery programs outside the SR. Nevertheless, the
SR fall-run Chinook salmon remains genetically distinct from similar fish in other basins.
Phenotypic characteristics have shifted in apparent response to environmental changes
from hydroelectric dams (Connor, Sneva et al. 2005).
The ICBTRT has defined only one extant population for the SR fall-run Chinook salmon,
the lower SR mainstem population. This population occupies the SR from its confluence
with the Columbia River to Hells Canyon Dam, and the lower reaches of the Clearwater,
Imnaha, Grande Rhonde, Salmon, and Tucannonh Rivers (ICBTRT 2003).
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