206 
Fishery Bulletin 95(2), 1997 
Increase in bottom salinity 
<D 
> 
(0 
CD 
C 
0 
Q_ 
C 
0 
C/) 
CO 
0 
O 
c 
-3-2-10 1 2 3 
Discriminant Function 1 
Figure 5 
Station associations based on results of the discriminant function analysis 
using the key discrimination factors salinity and percent gravel. 
• Group I 
O Group II 
a Group III 
v Group IV 
< Group V 
> Group VI 
■ Group VII 
ing 21 families offshore of central 
Oregon at depths of 40-1,829 m. 
Fargo and Tyler (1991) reported more 
than 50 species of demersal fish in 
Hecate Strait, British Columbia. Spe- 
cies diversity seems to be somewhat 
lower in our study area than off Or- 
egon, where diversity indices varied 
from 0.7 to 2.47 (Pearcy, 1978). 
As noted, in terms of biomass and 
abundance, B. saida was the most 
common species in our study area; 
however, this species varied exten- 
sively between stations and years. 
For example, at station 15 (off Cape 
Lisburne), B. saida accounted for 
0.23% of the number and 0. 18% of the 
biomass. In contrast, at station 27 
(northwest of Point Franklin), 100% 
of the catch comprised B. saida. 
Observed trends of fish distribu- 
tion, abundance, biomass, and as- 
semblages were qualitatively similar to those of epi- 
faunal mollusks found by Feder et al. (1994) but not 
to those of infaunal mollusks. These qualitative simi- 
larities suggest that common variables are influenc- 
ing the distribution of fishes and epifaunal mollusks 
in the study area. Feder et al. (1994) found epifau- 
nal mollusk abundance and biomass to be highest 
along the coast, with very high values adjacent to 
Point Hope and north of Cape Lisburne. Addition- 
ally, the 5 epifaunal mollusk assemblages described 
by Feder et al. were configured in the same way as 
the fish assemblages described in our study 7 . How- 
ever, in contrast to results from our study, abundance 
and distribution of infaunal mollusks were highest 
north of and adjacent to the hydrographic front as- 
sociated with the Alaska Coastal Current (ACC) and 
along the coast north of Icy Cape and adjacent to or 
north of Cape Lisburne. The multivariate, cluster, 
Table 4 
Discriminant function analysis of environmental factors 
with Chukchi Sea demersal fish abundance as the class 
criterion. Significant relationships are underlined. 
Standardized discriminant 
function coefficients 
Independent variable 
1st axis 2nd axis 
Bottom salinity 
Percent gravel 
Percent variance 
Eigen value 
0.94189 0.48469 
-0.14688 1.04905 
71.81 28.19 
1.887 0.741 
discriminant, and principal component analyses 
yielded similar results: stations tended to be grouped 
by bottom salinity and percent gravel. 
Because of the relatively shallow (30-50 m) depth 
of the northern Chukchi Sea and its gradual, fea- 
tureless northward slope (Fig. 1), it seems surpris- 
ing that the principal component analysis identified 
depth as a significant variable. Depth may have been 
significant because it acted in concert with other fac- 
tors, such as sediment (which tends to be relatively 
coarse, grading to muds containing various proportions 
of gravel and sand) on the inner shelf between Point 
Hope and Point Barrow (Sharma, 1979; Naidu, 1988). 
Fargo and Tyler (1991) found assemblages related 
to depth and sediment type, where sediment type 
Table 5 
Results of the principal component (PC) analysis using both 
environmental factors and infaunal and epifaunal abun- 
dance. Significant relationships are underlined. 
Variable 
PCI 
PC2 
PC3 
Percent sand 
0.563 
-0.451 
-0.643 
Percent gravel 
0.663 
-0.421 
0.771 
Depth 
-0.796 
0.398 
-0.238 
Bottom salinity 
—0.882 
0.118 
0.105 
Epifaunal abundance 
0.461 
0.861 
0.060 
Infaunal abundance 
0.318 
0.880 
0.040 
Cumulative variance 
0.371 
0.649 
0.805 
Eigenvalue 
2.596 
1.951 
1.095 
