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�..� Table 3. Simpson's Index of Diversity for each sample station, based on all macroinvertebrate <br />taxa identified. <br />Diversity <br />Station March October <br />D1 <br />0.30 <br />0.17 <br />D2 <br />0.18 <br />0.16 <br />D3 <br />0.16 <br />0.51 <br />D4 <br />0.13 <br />0.11 <br />D5 <br />Q,A <br />Q1Q <br />Mean <br />0.18 <br />0.21 <br />U1 <br />0.17 <br />0.11 <br />U2 <br />0.16 <br />0.18 <br />U3 <br />0.59 <br />0.07 <br />U4 <br />0.01 <br />0.02 <br />U5 <br />QZ <br />Qa <br />Mean: <br />0.24 <br />0.10 <br />Note: Simpson's Index of Diversity, ,1, is calculated as follows: I = E p;2, where p, is the <br />proportion of the total number of individuals (all species) in species i. <br />Fish Populations: <br />Fish populations were not assessed by this study, however, we contacted Sherman Hebein, <br />Fisheries Biologist with the Colorado Division of Wildlife's Southwest Region headquartered <br />in Montrose. According to Hebein, the Division does not have a regular fish sampling <br />program in the North Fork River. The only data that he had from the North Fork in the <br />vicinity of this study was from a survey conducted in July, 1976, at a site approximately 1 <br />mile downstream of Somerset. The survey was conducted using electrofishing methods along a <br />500 ft reach of the river. Six species were recorded, including 1 brown trout, 10 bluehead <br />suckers, 17 white suckers, 5 flannelmouth suckers, 60 speckled dace, and 53 mottled sculpins. <br />The brown trout accounted for only 1 percent of the biomass captured. During the same <br />summer, two other sites farther downstream were surveyed, one a half mile upstream of the <br />confluence with the Gunnison River, and the other just below the Hotchkiss National Fish <br />Hatchery. The most productive of those two sites was the one near the hatchery, where they <br />captured 47 rainbow trout, 2 brown trout, 24 mottled sculpins, 3 white suckers, 2 <br />flannelmouth suckers, 8 bluehead suckers, and 1 roundtail chub. At the site near the <br />confluence, they captured 7 mottled sculpins, 26 speckled dace, and 1 roundtail chub. <br />According to a report from the Colorado Division of Wildlife by Woodling (1985), the North <br />Fork should also support populations of longnose dace, longnose sucker, and fathead <br />13 <br />