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METHODS Size specific sampling techniques were employed for larval and adult individuals. Habitats sampled for individual species differed spatially and temporally, but not representatively at the selected life stages. Habitats sampled for adult fishes consisted of main channel shorelines, flooded tributaries, mouths of ephemeral washes, and main channel cobble bars. Sampling for razorback sucker adults was conducted on the ascending limb of the hydrograph in April-May of 1994 and in May-June of 1995. Colorado pikeminnow adult sampling occurred in late June in both 1994 and 1995. Razorback sucker adults were only sampled using electrofishing. Sampling for razorback sucker adults consisted of three electrofishing trips in 1994 and four trips in 1995. In 1994, trammel nets were used to sample for adult Colorado pikeminnow in the vicinity of Millard Canyon. In 1995, pikeminnow adults were sampled with both trammel nets and electrofishing (refer to Appendix table 1 for a summary of sampling efforts for all life stages) Electrofishing was conducted from a 4.8-m long aluminum john boat with AC power supplied from a 5 KW generator and converted to pulsed DC by a Coffelt Variable Voltage Pulsator (WP-15). Metered readings of main channel shocking values were 300-500 V, 5-7 A, and 20-40 Hz depending on water conditions. Sampling of flooded tributaries and ephemeral washes was hampered by high water conductivities (>1500 ,uS). Trammel nets used were 23 m X 1.8 m with inner/outer mesh sizes of 2.5/25 cm, respectively. Nets were sampled either by drifting them through runs or by securing one end to shore. Passive set trammel nets were checked for fish every 2 hours and were set in place for up to 5 hours. All fish captured via electrofishing and trammel nets were weighed and measured and returned to the river as close to point of capture as possible. Any razorback sucker or Colorado pikeminnow greater than 175 mm TL were implanted with a PIT tag unless previously tagged. Larval fishes of both species were sampled with quatrefoil light traps and/or seines. Light traps were versions commercially produced by Southern Concepts (Birmingham, AL) having slit widths of either 2, 4, or 6 mm with 4 mm being most common. Traps were set by tying them to emergent aquatic or overhanging terrestrial vegetation at dusk and were retrieved the following morning before dawn. Seine hauls were completed using a one person larval seine (1 mZ, 0.8 mm mesh) or a beach seine (4 m X 1.5 m, 1.25 mm mesh). Seining was conducted in late afternoon or early evening in association with setting of light traps. Larger fish captured in seines were processed (identified and counted) in the field while smaller fish and light trap samples were preserved in 100% ethanol and transported to the Larval Fish Laboratory, Colorado State University, Ft. Collins, Colorado for processing. Larval razorback sucker sampling in 1994 began in early May (coinciding with initial captures of sucker larvae below the middle Green River spawning site} and ended in mid-June. Sampling in 1995 extended from 19 April (when main channel temperature reached 14°C) until mid-July. Sampling for Colorado pikeminnow larvae was conducted in late June. Due to overlap in suspected spawning seasons, sampling for Colorado pikeminnow larvae coincided with the latter part of razorback sucker larval sampling. Habitats sampled with light traps included zero velocity nursery areas including main channel backwaters and flooded mouths of tributaries and ephemeral washes. Seine hauls were also conducted in low to zero velocity habitats. 3