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I I I I I I I I I I I I I I I I I I I CHAPTER 2--FISH By Gordon Mueller (USGS), Richard Wydoski (BaR), and Quentin Bradwisch (UDWR) METHODS Sampling was conducted to determine fish community composition, relative abundance, and changes since previous surveys (Holden and Irvine 1975) and to examine sampling gear efficiency. Sampling techniques included both active and passive netting techniques using the following equipment: a 6 rnm bar mesh (1.3 X 10 m) seine, a 12 mm (1.3 x 15 m) trammel net, a 80 cm diameter, 2 hoop fyke net, and two collapsible minnow traps. Sampling was conducted on the declining limb of spring runnoff and weather conditions were relatively cool and dry. The river was turbid, carrying a substantial sediment and debris load. Visibility was <10 cm which made it difficult to sample or make any visual observations. Gage reading at the headwaters of the Escalante River (station#09337500) fell from 32 to 6cfs during the course of the survey. Downstream tributaries contributed additional flows increasing the river to an estimated volume of 155 cfs (131-191 cfs [3.7-5.4 m3/sD. A small volume (<2 cfs) of water was flowing from Harris Wash and Coyote Gulch but the stream beds at Fence, Choprock, and Steven's canyons were dry. The flow from Harris Wash was broad (3-5 m) and quite shallow (2-5 cm) and we observed schools of small (<3 cm) suckers and speckled dace. Fence Canyon had a series of spring fed pools, some more that a meter deep and several meters in length. The pools supported what appeared to be multi year classes of green sunfish and fathead minnows which suggests the pools are permanent features. These are the same species reported to be common in pools found in other side canyons by both Holden and Irvine (1975) and McAda et al. (1977). Slightly more water (est 2-4 cfs) was flowing from Coyote Gulch. At its confluence with the river it formed a large (7-10 m), long (50 m), shallow pool (0.5 m) that was full oftadpoles. We walked upstream approximately 1 krn. The stream bed was composed of fine, drifting sand. Only a couple of small fish (suckers or dace ?) were observed. Flow Measurements--Physical measurements of the reach's length, width (3 locations), mid- channel depths, and maximum depth were recorded. Surface water velocities were measured by timing floats released in mid-channel. A gross flow estimate was calculated using the following formula: R= Y{TDaL , were R = volume (m3/sec), W = stream width, Da = depth X constant .8 for bottom roughness, L = length, and T = average float time in seconds (Lagler 1950). Other more complex as well as smaller areas were sampled but not measured. Seining-- The seine was used to collect both quantitative and qualitative information. At each study site a reach relatively free of major obstructions was sampled using three-pass, depletion seining. Prior to sampling the trammel net was set downstream to block fish escape. The sample reach was seined starting upstream and working toward the blocking net. Fish collected 10