202 
Fishery Bulletin 95(2), 1 997 
Table 2 
Estimated mean abundance (fish/km 2 ) of demersal fishes collected at stations sampled during both 1990 and 1991 in the north- 
eastern Chukchi Sea. Species sequence is based on the overall abundance of 1990 (Table 1), and the probability value ( P ) is from 
the Wilcoxon signed-ranks test. Species diversity was calculated from Shannon’s Index (H). 
Station 6 
Station 16 
Station 21 
Station 22 
Station 23 
Station 43 
Station 36 
Station 27 
Species 
1990 
1991 
1990 
1991 
1990 
1991 
1990 
1991 
1990 
1991 
1990 
1991 
1990 
1991 
1990 
1991 
Boreogadus saida 
56,373.8 
14,183.5 
22,386.5 2,273.4 
32,184.6 
393.0 
20,475.3 
8,527.7 
3180 
2,379.4 
13,684.7 
5,090.2 
19,104.8 
2,139.4 
3,017.3 
2,180.3 
Gymnocanthus 
tricuspis 
207.3 
3,047.0 
157.6 
0 
386.8 
0 
494.5 
124.8 
778.3 
2,041.0 
160.2 
244.5 
728.4 
969.1 
0 
0 
Myoxocephalus 
verrucosus 
324.7 
0 
0 
27.0 
630.5 
0 
0 
568.8 
1,163.1 
1,016.2 
170.6 
189.8 
246.7 
702.2 
0 
0 
Enophrys diceraus 
59.4 
1,932.8 
11.6 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Myoxocephalus sp. 
0 
0 
712.2 
0 
599.4 
0 
608.9 
0 
6 
55.9 
0 
11 
0 
0 
0 
0 
Pleuronectes aspera 
400.8 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Hippoglossoides 
robustus 
0 
37.5 
1,113.5 
0 
229.7 
0 
254.8 
10.8 
0 
0 
66.8 
88.2 
0 
33.4 
0 
0 
Lycodes raridens 
0 
102.4 
0 
54.1 
0 
0 
1,061.0 
0 
0 
0 
550.5 
22.0 
0 
0 
0 
34.6 
Myoxocephalus sp.2 
0 
1,621.1 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Lycodes palearis 
0 
37.5 
492.1 
162.4 
199.8 
0 
416.1 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Lumpenus fabncii 
22.1 
651.8 
147.3 
0 
129.8 
0 
124.0 
0 
0 
0 
43 
111.0 
0 
11.1 
0 
0 
Triglops pingeli 
0 
519.1 
0 
0 
27.4 
0 
0 
0 
57.8 
111.8 
375.4 
22.2 
49.1 
11.1 
0 
0 
Clupea harengus 
221.8 
0 
10.7 
0 
804.1 
0 
26 
0 
0 
0 
34.1 
0 
0 
0 
0 
0 
Gadus 
macrocephalus 
830.6 
0 
102.7 
0 
0 
0 
62.5 
0 
6 
0 
0 
0 
0 
0 
0 
0 
Number of 
other species 
2,853.2 
6,807.0 
492.1 
0 
376.5 
0 
551.6 
135.6 
28.9 
86.3 
178.0 
99.2 
49.0 
100.3 
0 
251.1 
P 
0.562 
0.003 
0.001 
0.004 
0.444 
0.42 
0.975 
0.498 
Number of species 
19 
24 
15 
4 
15 
1 
17 
8 
7 
9 
14 
13 
8 
10 
1 
5 
Total number of 
species, both 
years combined 
32 
17 
15 
19 
10 
18 
14 
5 
Percent in common 
both years 
40.6 
17.6 
6.7 
42.1 
60 
50 
28.6 
20 
Species diversity 
0.47 
1.83 
0.62 
0.4 
0.52 
— 
0.74 
0.4 
1.01 
1.25 
0.53 
0.54 
0.38 
1.18 
— 
0.37 
There was a trend towards higher species richness 
in the southern and offshore areas than in the north- 
ern and inshore areas (Fig. 3). The greatest num- 
bers of species per station (19) were recorded at sta- 
tions 6 (Point Hope), 45 (Point Lay), and 48 (Ledyard 
Bay) in 1990 and at station 6 (23 species) in 1991 
(Fig. 3). The fewest species (2 or 3) occurred at four 
stations in the more northern area (stations 28 
through 32). There was a tendency for the stations 
south of Icy Cape to have 11 or more species and 
those stations to the north to have 10 or less; the 
majority of the latter had fewer than 8 species. 
The number of species at stations sampled during 
both 1990 and 1991 differed considerably (Table 2). 
For example, catches at three stations northeast of 
Cape Lisburne consisted of 15 and 17 species in 1990 
but in 1991 comprised 1 to 8 species. In contrast, 
farther north at station 21, 1 species was collected 
in 1990 and 5 species in 1991. 
Those stations with a species diversity of >0.90 oc- 
curred south of a line extending south-westward from 
Point Franklin. The greatest species diversity (1.99) 
occurred at station 45 off Point Lay; species diver- 
sity at two stations off Cape Lisburne (15 and 14) 
was nearly as large (1.56 and 1.87, respectively). 
Nearly all stations with a diversity of >1.0 occurred 
alongshore from Point Franklin to Point Hope. Low- 
est species diversity occurred at station 39 (0.02). 
Evenness followed the same pattern as species di- 
versity indices (Fig. 3). 
Assemblages 
Fishes collected in 1990 formed, at a similarity level 
of 0.5-0. 6, three nearshore (I, III, and V) and three 
offshore (II, IV, and VI) associations (Fig. 4). One sta- 
tion (15) was not classifiable (Fig. 4). Two clusters of 
stations formed an association (I) off the Lisburne 
