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

and five-year old fish, after two to three years in the ocean. A small fraction of the fish
return as three year-old “jacks”, heavily predominated by males.
Status and Trends
SR spring/summer-run Chinook salmon were originally listed as threatened on April 22,
1992 (57 FR 14653). Their classification was reaffirmed following a review on June 28,
2005 (70 FR 37160). Although direct estimates of historical annual SR spring/summer
Chinook salmon returns are not available, returns may have declined by as much as 97%
between the late 1800s and 2000. According to Matthews and Waples (1997), total
annual SR spring/summer Chinook salmon production may have exceeded 1.5 million
adult fish in the late 1800s. Total (natural plus hatchery origin) returns fell to roughly
100,000 spawners by the late 1960s (Fulton 1968) and were below 10,000 by 1980.
Between 1981 and 2000, total returns fluctuated between extremes of 1,800 and 44,000
fish. The 2001 and 2002 total returns increased to over 185,000 and 97,184 adults,
respectively. The 1997 to 2001 geometric mean total return for the summer run
component at Lower Granite Dam was slightly more than 6,000 fish, compared to the
geometric mean of 3,076 fish for the years 1987 to 1996. The 2002 to 2006 geometric
mean of the combined Chinook salmon runs at Lower Granite Dam was over 18,000 fish.
However, over 80% of the 2001 return and over 60% of the 2002 return originated in
hatcheries (Good, Waples et al. 2005). Good et al. (2005) reported that risks to
individual populations within the ESU may be greater than the extinction risk for the
entire ESU due to low levels of annual abundance and the extensive production areas
within the SR basin. Year-to-year abundance has high variability and is most pronounced
in natural-origin fish. Although the average abundance in the most recent decade is more
abundant than the previous decade, there is no obvious long-term trend. Additionally,
hatchery fish are faring better than wild fish, which comprise roughly 40% of the total
returns in the past decade. Overall, most populations are far below their respective
interim recovery targets.
Regarding population growth rate (lambda), long-term trends are