Keller et al Variations in eastern North Pacific demersal fish biomass, 2003-10 
217 
shallow 
55-183 m 
shallow 
55-183 m 
in 
a> 
O 
CD 
CL 
CO 
18 
i i 
♦ * 
18 
16 
* # * * 
16 
^=0.34 
14 
14 
18 
mid-depth 
184-549 m 
18 
* 
16 
* 
16 
T" 
14 
y=-0.200x+417.2 
14 
d=0 49 
12 
12 
15 
deep 
15 
550-1280 m 
14 
i , } i 
14 
13 
i * i 
T I 
13 
12 
1 
r 2 =0 19 
t * 
12 
11 
11 
18 
all depths 
18 
55-1280 m 
16 
16 
14 
i 
"r~ 
14 
y=-0 160x+336 3 
12 
r*=0.45 
12 
2002 2004 2006 2008 2010 
* i 
y=1 086x+17 0 
r*=0 71 
mid-depth 
184-549 m 
^"1" * 
y=0.757x+15.5 
r '=0 68 
deep 
550-1280 m 
1 i 
f 
all depths 
55-1280 m 
r *=0 20 
y=0 691x+15 0 
r>=0.80 
-1 -0 5 0 0 5 1 1.5 
Year 
PDO 
Figure 7 
Coast-wide estimates of species richness (± standard error) by depth (shallow 
55-183 m; mid 184-549 m; deep 550-1280 m; all depths combined 55-1280 
m) versus year and annual Pacific Decadal Oscillation (PDO) values, 2003-10. 
Regression equations for relationships with significant (P<0.05) trends are 
displayed. Coefficients of determination (r 2 ) are shown here for the regression 
equations while significance levels ( P ) are shown in Table 2. 
California slickhead ( Alepocephalus tenebrosus), deep- 
sea sole (Embassichthys bathybius), giant grenadier 
( Albatrossia pectoralis ), Pacific flatnose ( Antimora mi- 
crolepis), Pacific grenadier ( Coryphaenoides acrolepis ), 
roughtail skate (Bathyraja trachura), snakehead eel- 
pout ( Lycenchelys crotalinus), twoline eelpout (Bothro- 
cara brunneum), and grooved Tanner crab ( Chionoece - 
tes tanneri), no significant relationship with time was 
detected over the survey period. Thornyheads were the 
sole group to exhibit an overall positive correlation 
with time (with higher biomass occurring in recent 
years). Shallow to mid-water species (mean depth <500 
m) consisting of groups composed of cartilaginous fish, 
flatfish, shelf roekfish, or a mixed subgroup of fish, and 
overall biomass all significantly declined over time. 
These declines occurred despite the classification of the 
west coast fishery as having the lowest overall exploita- 
tion rates of ten ecosystems examined by Worm et al. 
(2009) and multiple management measures introduced 
to reduce catch. 
