Stevenson et al.: Patterns of species richness, diversity, population density, and distribution in the skates of Alaska 
29 
Table 2 
Mean skate species richness (no. of species/haul, with standard error in parentheses) by subregion and depth range for bottom- 
trawl surveys conducted in the eastern Bering Sea (shelf and slope), Aleutian Islands, and Gulf of Alaska from 1999 through 2004. 
Subregion 
Depth range (m) 
1 
2 
3 
4 
5 
6 
Total 
Bering Sea shelf 
<50 
51-100 
101-200 
Total 
0.51 (0.04) 
0.93 (0.03) 
1.52 (0.06) 
0.94(0.03) 
0.79 (0.03) 
1.06(0.02) 
1.58(0.06) 
1.07(0.02) 
0.72 (0.11) 
0.96 (0.02) 
1.47 (0.04) 
1.21 (0.02) 
0.67 (0.02) 
0.98 (0.01) 
1.51 (0.03) 
1.07 (0.01) 
Bering Sea slope 
201-600 
601+ 
Total 
2.43 (0.11) 
1.91 (0.16) 
2.25 (0.09) 
3.16 (0.32) 
3.19 (0.24) 
3.17 (0.20) 
2.22 (0.22) 
2.94 (0.18) 
2.58 (0.15) 
3.59 (0.18) 
2.63(0.28) 
3.13 (0.17) 
2.87 (0.40) 
1.52 (0.20) 
2.05 (0.22) 
3.81 (0.16) 
2.27 (0.24) 
3.22 (0.16) 
2.91 (0.08) 
2.39 (0.09) 
2.69 (0.06) 
Aleutian Islands 
<100 
101-200 
201+ 
Total 
0.59 (0.10) 
0.89 (0.11) 
0.69 (0.12) 
0.77 (0.07) 
0.52 (0.06) 
0.59 (0.07) 
0.93(0.08) 
0.70(0.04) 
0.51 (0.08) 
0.77 (0.06) 
1.04 (0.07) 
0.84(0.04) 
0.38(0.04) 
0.50(0.07) 
0.90 (0.07) 
0.60 (0.04) 
0.46 (0.03) 
0.69 (0.04) 
0.92 (0.04) 
0.72 (0.02) 
Gulf of Alaska 
<100 
101-200 
201+ 
Total 
0.25(0.03) 
0.27 (0.05) 
0.30 (0.10) 
0.26 (0.02) 
0.39(0.04) 
0.70 (0.06) 
1.02(0.10) 
0.67(0.04) 
0.39 (0.04) 
0.74(0.04) 
0.65(0.07) 
0.60 (0.03) 
0.44 (0.09) 
0.46 (0.06) 
0.47 (0.07) 
0.46 (0.04) 
0.27 (0.12) 
0.26(0.07) 
0.40 (0.08) 
0.33 (0.05) 
0.34 (0.02) 
0.60(0.03) 
0.64 (0.04) 
0.51 (0.02) 
Table 3 
Shannon’s diversity index ( H' ) by subregion and depth range for bottom-trawl surveys conducted in the eastern Bering Sea (shelf 
and slope), Aleutian Islands, and Gulf of Alaska from 1999 through 2004. 
Subregion 
Depth range (m) 
1 
2 
3 
4 
5 
6 
Total 
Bering Sea shelf 
<50 
0.02 
0.01 
0.00 
0.01 
51-100 
0.15 
0.06 
0.03 
0.09 
101-200 
0.57 
0.62 
0.34 
0.46 
Total 
0.28 
0.20 
0.25 
0.24 
Bering Sea slope 
201-600 
1.48 
1.44 
1.33 
1.42 
1.67 
1.70 
1.71 
601+ 
1.47 
1.33 
1.30 
1.07 
1.10 
0.99 
1.46 
Total 
1.65 
1.42 
1.57 
1.38 
1.85 
1.85 
1.82 
Aleutian Islands 
<100 
0.72 
0.46 
0.70 
1.65 
1.27 
101-200 
0.80 
1.20 
1.04 
1.52 
1.13 
201+ 
1.31 
1.22 
0.97 
0.93 
1.10 
Total 
0.94 
1.32 
1.18 
1.33 
1.33 
Gulf of Alaska 
<100 
1.01 
0.87 
0.93 
0.52 
0.17 
0.91 
101-200 
1.43 
1.53 
1.32 
0.90 
0.90 
1.42 
201+ 
0.79 
1.51 
1.35 
0.68 
1.56 
1.44 
Total 
1.33 
1.64 
1.46 
1.00 
1.44 
1.53 
