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. DRAFT 3.0 ME'IBODOr.cx:;y . . This investigation consisted of two work phases, during each of the 2 years of study. Phase one involved the capture and implant of radiotransmitters into 10 adult Colorado squawfish and 10 adult razorback suckers. A total of 20 different fish of each species was radiotagged over the 2-year period. phase one was conducted in two 10-day periods from mid to late October. Phase two consisted of radiotracking the fish over a 4-month winter period from December through March (Table 1). 3.1 IQJIPMENI' . Since the study area encompassed flatwater and whi tewater regions, both aluminum jonboats and whitewater rafts were used. The jonboats were 16 feet long, and powered by 25 or 35 hp Mercury outboards. One 14-foot jonboat with a 9.9 hp outboard was stored at Echo Park because winter road conditions often prohibi ted trailoring a boat into the area. The whi tewater rafts included 17 and 18-foot Riken Havasus with rowing frames and equiped with XD-25 hp Mercury outboards for flatwater areas. A 16-foot jonboat and the l8-foot Havasu raft were equipped with electrofishing systems which were removed later for tracking. During January and February of 1988, when the river was frozen through most of the study area, access was by vehicle along shoreline roads. Much of the tracking was done with cross-country skis on the frozen and snow-covered river channel. Snowmobiles and quadratracks were found to be impractical because of the unstable and rough nature of the river ice and the heavy shoreline vegetation. . . 3.1.1 Electrofishing . All adult Colorado squawfish and razorback suckers used in this study were captured by electrofishing. Electrofishing was conducted during two field trips in October (Table 1) primarily along shorelines or other suitable habitat accessible by boat. A 220-volt DC system was used. It was powered by either a 4.5-kilowatt EMS Honda generator or a 3.5-kilowatt Homelite generator and controlled by a Coffelt VVP-15 variable voltage pulsator. The normal operating level was 90-200 volts and 4-10 amps, at 80 pulses per second with a 40 percent pulse width. . . One or two netters dipped the fish from the bow of the boat. Actual electrofishing time in seconds was recorded on the internal VVP-15 timers, and used in calculating catch per unit effort (CPE) as numbers of fish per 10 hours of effort. Adult squawfish and razorback suckers were held in live wells for transport to a nearby mobile surgery station. Data from electrofishing runs, including all pertinent data on target species, were recorded on field data sheets provided by ms. Numbers of other species of fish were counted or estimated by netters and recorded. . 5 .