218 
Fishery Bulletin 1 10(2) 
80,000 
60,000 
40,000 
20,000 
Rockfish 
■o— Flatfish 
■*— Sablefish 
o Thornyheads 
400,000 
300,000 
200,000 
100,000 
B 
-° Pacific hake 
- Total groundfish 
1980 
1985 
1990 
1995 
Year 
2000 
2005 
2010 
Figure 8 
Landed catch (in metric tons, t) for (A) rockfish ( Sebastes spp.), flatfish, 
sablefish ( Anoplopoma fimbria ), and thornyheads (Sebastolobus spp.), 
and (B) total groundfish and Pacific hake (Merluccius productus), off 
Washington, Oregon, and California from 1980 through 2010. Data 
were obtained from the Pacific Fisheries Information Network: http :// 
pacfin.psmfc.org/pacfin pub/data.php (accessed September 2011). Note 
the different scales for overall catch and Pacific hake (0-400,000 t) and 
for the remainder of the species (0-80,000 t). 
To evaluate the decline in overall groundfish biomass 
indices off the western United States, despite much re- 
duced fishing effort, we investigated two potential and 
perhaps overlapping factors: depletion after strong re- 
cruitment and environmental effects. Decreases in total 
biomass indices occur within an ecosystem when catch 
is greater than net population growth. To evaluate the 
contribution of these factors to the observed decline in 
biomass, we separated the species examined here into 
subgroups based on the presence or absence of strong 
recruitment during the late 1990s. We used information 
contained in 24 stock assessments to assign species 
to subgroups with strong recruitment (primarily in 
1999), without strong recruitment, and with unknown 
recruitment. We developed regressions models for each 
subgroup and overall versus year, annual PDO indices, 
and including both variables. We assumed that year 
was a good proxy for depletion of exceptionally strong 
cohorts as they recruited to the groundfish fishery in 
subsequent years (Haltuch and Hicks, 2009). For mul- 
tiple species with highly successful recruitment events 
in 1999, there has been a gradual decline in biomass 
since 2003. Regression models for total biomass of these 
species were best fitted by time, whereas regression 
models for those species without strong recruitment 
were best fitted to variation in climate as measured by 
annual PDO indices. Our analysis also indicated that 
for models comparing summed biomass for groups with 
