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

Status and Trends
The OC coho salmon ESU was listed as a threatened species on February 11, 2008 (73
FR 7816). The most recent NMFS status review for the OC coho salmon ESU was
conducted by the BRT in 2003, which assessed data through 2002. The abundance and
productivity of OC coho salmon since the previous status review (Gustafson, Wainwright
et al. 1997) represented some of the best and worst years on record. Yearly adult returns
for this ESU were in excess of 160,000 natural spawners in 2001 and 2002, far exceeding
the abundance observed for the past several decades. These encouraging increases in
spawner abundance in 2000–2002 were preceded, however, by three consecutive brood
years (the 1994–1996 brood years returning in 1997–1999, respectively) exhibiting
recruitment failure. Recruitment failure is when a given year class of natural spawners
fails to replace itself when its offspring return to the spawning grounds three years later.
These three years of recruitment failure were the only such instances observed thus far in
the entire 55-year abundance time series for OC coho salmon (although comprehensive
population-level survey data have only been available since 1980). The encouraging
2000–2002 increases in natural spawner abundance occurred in many populations in the
northern portion of the ESU, which were the most depressed at the time of the last review
(Gustafson, Wainwright et al. 1997). Although encouraged by the increase in spawner
abundance in 2000–2002, the BRT noted that the long-term trends in ESU productivity
were still negative due to the low abundances observed during the 1990s (73 FR 7816).
Since the BRT convened, the total abundance of natural spawners in the OC coho salmon
ESU has declined each year (i.e., 2003-2006). The abundance of total natural spawners
in 2006 (111,025 spawners) was approximately 43% of the recent peak abundance in
2002 (255,372 spawners). In 2003, ESU-level productivity (evaluated in terms of the
number of spawning recruits resulting from spawners three years earlier) was above
replacement, and in 2004, productivity was approximately at replacement level.
However, productivity was below replacement in 2005 and 2006, and dropped to the
lowest level since 1991 in 2006.
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