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Fishery Bulletin 109(2) 
October+July tests H' at 160 m was significantly lower 
than that observed at shallower depths (Fig. 3). 
N did not differ significantly across months (ANO- 
VA, F[ 132 ]=1.7, P=0.18 and F (1 26] = 0.3847, P=0.68 in 
October+July and all-months tests, respectively) and 
there was no significant interaction between depth and 
month (ANOVA, F [3 32] = 2.3, P=0.08 and P [2 26) = 1.4, 
P=0.26 in October+July and all-months tests, respec- 
tively). In contrast, H' in the October+July test differed 
significantly by month (ANOVA, P| 132] =13.4, PcO.OOl), 
as well as the interaction between depth and month 
(ANOVA, F (3 32 |=:8.3275, P<0.001). Overall, H' was high- 
er in October than in July and the interaction term 
appears to be related to a strong seasonal change in 
H' at 80 m (Fig. 3). Month and the interaction between 
month and depth were not significant in the test for 
all-months (ANOVA, F^ 26] =2.0, P=0.15 and F (1 26] =1.7, 
P=0.2, respectively). 
Taxon-based analysis 
Depth was a significant predictor of assemblage struc- 
ture in all-months and in October+July CCA tests, 
and explained 44% (F (1 27 j = 19.1, P<0.001) and 34% 
(F[ 3 33] = 6.1, PcO.OOl) of the variances, respectively. 
Season explained a smaller proportion of the vari- 
ance (5%) in the October+July CCA test (F (1 33] =2.7, 
P<0.05) and was not a significant predictor in 
the all-months test (F^ 27] =1.9, P<0.18). Temporal 
shifts in depth distributions were negligible at the 
assemblage level; the joint variance explained by 
season and depth was zero for October+July and 
all-months analyses. 
The resulting tri-plots for each partial CCA 
(based on weighted averages of the species scores) 
simultaneously depict the centroid of the sites cod- 
ed for the constraining variables and the position 
(eigenvectors) of the species forming the response 
matrix. Examination of the depth partial CCA 
tri-plots for October+July and all-months analy- 
ses, indicated that the first CCA axis primarily 
separated shallow (20 and 40 m) and deep (80 
and 160 m) fish communities (Fig. 4). The spread 
of the variable centroids indicates the relative dif- 
ferences in species composition among the respec- 
tive depth and month factors (distant centroids 
are more dissimilar in species composition than 
close centroids). Species centered near the origin 
of the tri-plot have little to no association with 
the predictor variables included in the analyses, 
but those furthest from the origin have higher 
loadings, the strongest associations with the CCA 
axis, and contribute the most to differentiating 
sites that separate along the same axis. For the 
October+July samples, the second CCA axis also 
separated the 80- and 160-m fish assemblages 
(Fig. 4). Partial CCA results for the October+July 
and all-months samples confirmed that 160 m was 
dominated by spotted ratfish and small spiny dog- 
fish, but that Pacific hake (Merluccius productus), 
rex sole ( Glyptocephalus zachirus), and dover sole 
(Microstomus pacificus ) also typified that depth 
(Fig. 4). Furthermore, species that were associ- 
ated with both 80 and 160 m included large spiny 
dogfish, and quillback rockfish (Sebastes maliger), 
brown rockfish (Sebastes auriculatus), blackbelly 
eelpout (Lycodes pacificus ), Pacific tomcod (Mi- 
crogadus proximus ), walleye pollock ( Theragra 
chalcogramma) , shiner perch ( Cymatogaster ag- 
gregate), pile perch ( Rhacochilus vacca ), black tip 
poacher (Xeneretmus latifrons), slender sole ( Lyop - 
setta exilis), and plainfin midshipman ( Porichthys 
