214 
Fishery Bulletin 1 10(2) 
13.2 
12 8 
12.4 
12.0 
11.6 
11.2 
sharks, skates, ratfish 
L 
t 
y=-0.131x+275 
^=0.79 
* 
13.5 
13.3 
13.1 
12.9 
flatfish 
y=-0.027x+66 
^=0 58 
13.5 
13.0 
12.5 
12.0 
115 
% 11.0 
to 
>/> 
03 
E 13.5 
o 
CD 
13 0 
12.5 - 
shelf rockfish 
i 
4 
y=-0 18x+373 
r*=0.89 
others shallow-mid 
y=-0 138X+290 
^=0.89 
12.0 
* J 
12.4 
119 
114 
10.9 
10.4 
12.5 
12.4 
12.3 
12.2 
12.1 
slope rockfish 
ttti. 
i 
^=0 003 
thornyheads 
JtM 
1 I y=0.027x-41 1 
I ^=0 59 
12.3 
12.1 
119 
others deep 
I * * 
it tu 
^=0.0004 
1 1 7 4 
2002 2004 2006 2008 2010 
14 8 
14 6 
14 4 
14.2 -I 
total groundfish 
y=-0 091x+198 
^=0.93 
14.0 
2002 2004 2006 2008 
2010 
Figure 4 
Expanded coast-wide biomass indices (expressed as the natural log in metric 
tons, [t] ) and standard errors as a function of time (year) for 62 dominant 
demersal taxa collected during the 2003-10 groundfish survey, subdivided 
into seven subgroups (Table 1), and summed overall. Regression equations for 
subgroups with significant decreasing trends (P<0.05) over time and coefficients 
of determination (r 2 ) are displayed. 
the minimum AIC value occurred for models incorporat- 
ing both year and PDO indices combined (Table 2). The 
A- for the four biomass models indicate that none of the 
models are equivalent to the best model; however, the 
observed A- <7 for two of the four groups suggest some 
support for alternative models (Table 2). 
Species richness 
Species richness indices incorporated all fish collected 
during the 2003-10 surveys, including rare deep-water 
species and those not normally associated with the 
bottom. Regressions between species richness and year 
indicate near significant negative trends for mid-depth 
(P=0.06) and overall (P=0.08), but insignificant rela- 
tionships for shallow and deep depth strata (Fig. 7). 
With the exception of the deep depth stratum (P=0.20), 
significant positive relationships (P<0.01) were observed 
between species richness and the PDO. The number of 
fish species present within two depth strata (shallow and 
mid-depth) and overall increased during the warm PDO 
phase. Additionally, species richness indices declined 
within increasing depth strata (Fig. 7). 
Based on minimum AIC values, the models which 
provided the best fit to changes in species richness 
during the survey period were either models incor- 
porating only PDO indices (shallow, mid-depth, and 
overall) or models incorporating both year and PDO 
values (deep), but not models based solely on year 
(Table 2). 
