472 
Fishery Bulletin 108(4) 
Table t 
Fish taxa exhibiting significantly greater relative abundance (number of fish per hectare) across all stations over primary habi- 
tat types at Heceta Bank, OR, (rock ridge, boulder, cobble, and mud) during daytime or nighttime. Wilcoxon signed-rank test was 
used (*P<0.05, **P<0.01) to compare day and night relative abundance between habitat patches in closest geographic proximity 
within primary habitat types over all stations. Taxa are listed in order of relative abundance from top to bottom; primary habitat 
is listed in decreasing order of size from left to right, and numbers in parentheses are relative abundance during day or night. 
Taxon 
Rock ridge 
Boulder 
Cobble 
Mud 
Significantly more abundant during day 
unidentified juvenile rockfish ( Sebastes spp.) 
(1498)** 
(2123)* 
(632)** 
(150)* 
Puget Sound rockfish (S. emphaeus ) 
(2235)** 
(421)** 
pygmy rockfish (S. wilsoni ) 
(4878)** 
(46)* 
(634)** 
pygmy-Puget Sound complex (S. wilsoni and S', emphaeus ) 
(3240)* 
rosethorn rockfish (S. helvomaculatus) 
(249)** 
(291)* 
(124)* 
unidentified ronquil (Bathymasteridae) 
(16)** 
(43)* 
unidentified mottled sculpin (Cottidae) 
(30)** 
unidentified sculpin (Cottidae) 
(12)* 
(28)** 
unidentified mottled poacher (Agonidae) 
(12)* 
kelp greenling ( Hexagrammos decagrammus ) 
(6)* 
Significantly more abundant during night 
sharpchin rockfish (S. zacentrus ) 
(460)** 
(1134)* 
(5603)* 
(1656)* 
redstripe rockfish (S. proriger ) 
(90)* 
harlequin rockfish (S. variegatus) 
(103)** 
spotted ratfish (Hydrolagus colliei) 
(75)* 
(56)* 
unidentified hagfishes ( Eptatretus spp.) 
(45)* 
(64)* 
rex sole (Glyptocephalus zachirus) 
(69)* 
denotes a better “fit” of data) of 20.5 for three axes. 
After a +115° rotation, the first axis showed correlation 
with day (right side) and night (left side) sample units, 
explaining 22% of the variation in the data and revealed 
a mean stress of 49.8. The second axis explained an 
additional 30% of the variation in the data and showed 
a negative correlation with depth (Pearson’s r=0.141) 
and a mean stress of 29.1. The second axis also showed 
a positive correlation with substrate, and larger-size 
primary habitat was found in the first and second quad- 
rants of the graph and smaller-size primary habitat in 
the third and fourth quadrant. The third axis improved 
the cumulative coefficient of determination, r 2 , to 0.777 
with little additional stress; this axis enabled us to 
rotate the ordination in three dimensions to distinguish 
habitat and species and showed good correlations with 
the day-night and habitat-depth axes, but is not easily 
plotted. Higher dimensions showed little improvement 
in model fit. 
Taxa more abundant during the day (rosethorn rock- 
fish, pygmy rockfish, pygmy-Puget Sound rockfish com- 
plex, kelp greenling, and unidentified juvenile rockfish) 
showed a positive correlation along axes one and two 
and appear in the upper right quadrant of Figure 4. 
Puget Sound rockfish showed a correlation with the 
day-night axis, but this species was associated with 
greater depth and smaller-size substrate as primary 
habitat when compared to the other taxa that were 
more abundant during the day; this taxon appears in 
the lower right quadrant. Thus, this dominant day 
assemblage was observed mainly at shallow- to mid- 
depths over medium to large-size substrata. Taxa show- 
ing greater abundance during the night (spotted ratfish 
[Hydrolagus colliei], hagfishes, rex sole [Glyptocephalus 
zachirus], sharpchin rockfish [S. zacentrus], and harle- 
quin rockfish) showed a negative correlation along axes 
one and two. Thus, the dominant night assemblage was 
generally over deeper areas of medium- to small-size 
substrata of cobble and mud. 
Day and night species assemblages 
During the day within all stations, large densities of 
mostly small-size rockfish taxa were primarily found 
over shallow rock ridge, boulder, and cobble substrata 
(Table 1, Figs. 3 and 4). The four most dominant day 
taxa (both active and inactive) were pygmy rockfish, 
Puget Sound rockfish, pygmy-Puget Sound rockfish 
complex, and unidentified juvenile rockfish. Yellowtail 
rockfish (S. flavidus) were also an important component 
of the daytime assemblage, albeit less abundant and less 
dominant during night. Many of these taxa showed sig- 
nificantly greater abundance and activity over medium- 
to large-size habitat (cobble, boulder, and rock ridge) 
(Tables 1 and 2). Rosethorn rockfish showed the clearest 
diurnal pattern of all species (Table 2). Small rockfishes 
and yellowtail rockfish were more active during the day 
but did not exhibit clear inactivity during the night. 
