Keller et al. : Variations in eastern North Pacific demersal fish biomass, 2003-10 
211 
350.000 
280.000 
210,000 
140.000 
70.000 
0 
200.000 
150.000 
100.000 
50.000 
0 
75.000 
50.000 
25.000 
0 
75.000 
50.000 
25.000 
Pacific hake 
( Merluccius productus ) 
ft 
& 
c 
tj ft a 
& x 
LI L 
C=B 
□ 
15,000 
10,000 
4000 
3000 
2000 
1000 
Ai 
sablefish 
(Anoplopoma fimbria) 
A a, £ 
lingcod 
( Ophiodon elongatus) 
Hi, 
spotted ratfish 
(Hydrolag us collief) 
n n 
o LI Li U U 
ft A 
bocaccio 
( Sebastes paucispinis) 
fi a 
black eelpout 
( Lycodes diapterus) 
ft ft i ft 4 i ft 
350.000 
280.000 
210,000 
140,000 
70.000 
0 
180.000 
135,000 
90.000 
45.000 
0 
75.000 
50.000 
25.000 
50.000 
40.000 
30.000 
20.000 
10,000 
0 
15.000 
10.000 
'5000 
0 
3000 
2000 
spiny dogfish 
( Squalus acanthias) 
□ 0 fi 0 => ft 
sharpchin rockfish 
(Sebastes zacentrus) 
rex sole 
(Glyptocephalus zachirus) 
ft ft 
darkblotched rockfish 
( Sebastes cramen) 
fi a i fi a 
white croaker 
(Genyonemus lineatus) 
0 ■ »-* 
2003 2004 2005 2006 2007 2008 2009 20 1 0 
redbanded rockfish 
(Sebastes babcocki ) 
250.000 
200.000 
150.000 
100.000 
50.000 
0 
125.000 
100.000 
75.000 
50.000 
25.000 
0 
60.000 
40.000 
20.000 
40.000 
30.000 
20.000 
10,000 
0 
6000 
4000 
chilipepper rockfish 
( Sebastes goodei) 
shortbelly rockfish 
( Sebastes jordani) 
ft . i £ ft 
English sole 
(Parophrys vetutus ) 
o u u u 
giant grenadier 
(Albatrossia pectoralis ) 
A A A 
4 
flathead sole 
( Hippoglossoides elassodon) 
ft 1 
a s a 
2000 
1500 
1000 
500 
curlfin sole 
(Pteuronichthys decurrens) 
2003 2004 2005 2006 2007 2008 2009 2010 
2003 2004 2005 2006 2007 2008 2009 201 0 
Figure 3 
Decreasing trends in demersal biomass indices in metric tons (t) (±standard error) for 18 of 20 taxa caught 
in the Northwest Fisheries Science Center’s West Coast Groundfish Bottom Trawl Survey, 2003-10. With 
the exception of California skate and pygmy rockfish, all species exhibiting significant (P<0.05) or near- 
significant (P<0.1Q) decreases in biomass indices over time are shown. 
amount of variation in biomass was explained by the 
PDO indices for those species with no strong recruit- 
ment during the late 1990s. We used AIC to determine 
which model (i.e., based on year, PDO indices or com- 
bined) provided the best fit to the data for each group 
(Table 2). For species with strong recruitment, the re- 
gression of biomass versus year had the minimum AIC 
value; for species without strong recruitment the model 
incorporating PDO indices provided the best fit. For 
both other groups (unknown recruitment and overall), 
