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

the 1950s. The vast majority of these have been derived from local late-returning adults.
Returns to hatcheries have accounted for 57% of the total spawning escapement.
However, the hatchery contribution to spawner escapement is probably much higher than
that due to hatchery-derived strays on the spawning grounds. The genetic similarity
between Green River late-returning Chinook salmon and several other late-returning
Chinook salmon in Puget Sound suggests that there may have been a significant and
lasting effect from some hatchery transplants (Marshall, Smith et al. 1995).
Overall, the use of Green River stock throughout much of the extensive hatchery network
in this ESU may reduce the genetic diversity and fitness of naturally spawning
populations (Good, Waples et al. 2005).
Hydromodification Projects
More than 20 dams occur within the region’s rivers and overlap with the distribution of
salmonids. A number of basins contain water withdrawal projects or small
impoundments that can impede migrating salmon. The resultant impact of these and land
use changes (forest cover loss and impervious surface increases) has been a significant
modification in the seasonal flow patterns of area rivers and streams, and the volume and
quality of water delivered to Puget Sound waters. Several rivers have been
hydromodified by other means including levees and revetments, bank hardening for
erosion control, and agriculture uses. Since the first dike on the Skagit River delta was
built in 1863 for agricultural development (Ruckelshaus and McClure 2007), other basins
like the Snohomish River are diked and have active drainage systems to drain water after
high flows that top the dikes. Dams were also built on the Cedar, Nisqually, White,
Elwha, Skokomish, Skagit, and several other rivers in the early 1900s to supply urban
areas with water, prevent downstream flooding, allow for floodplain activities (like
agriculture or development), and to power local timber mills (Ruckelshaus and McClure
2007).
Over the next few years, however, a highly publicized and long discussed dam removal
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