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I I I I I I I I I I I I I I I I I I I 3.0 METHODOLOGY This invp.stigation consisted of two phases. Phase I involved capturing 10 adult Colorado squawfish and 10 adult razorback suckers in mid to late October and surgically implanting each with a radiotransmitter. Phase 1/ consisted of six 10-day tracking and monitoring trips over a 5-month winter period from November through March (Table 2). The same general approach was used for both years of the investigation: year 1 = 1986-87; year 2 = 1987-88. Twenty different fish of each species were radiotagged over the 2-year period (See Appendix A). All data on fish movement and habitat use were based on these 40 radiotagged fish, although 1 Colorado squawfish and 3 razorback suckers were excluded from the database for various reasons. In year 1, all 10 Colorado squawfish and 8 of the 10 razorback suckers were included. No data were collected on razorback sucker GR-6110, since the partially decomposed carcass with transmitter was found shortly after release. Also, the data associated with fish GR-129 were not used, since this fish was suspected of being a hybrid of a razorback and flannel mouth sucker; such crosses have been reported (McAda 1977). We felt that data associated with this fish might not represent the behavior of a razorback sucker. In year 2, the data from 9 of the 10 radiotagged Colorado squawfish were used as was the data from 9 of the 10 razorback suckers. None of the data associated with Colorado squawfish OR-3237 were used. since the fate of the fish remains unknown; only the radiotransmitter was found on a dry sand bar. Although Colorado squawfish OR-3236 was also presumed dead. data from this fish were used in the analysis. since we are reasonably certain that the fish was healthy during our observations. We believe that this fish was taken by an avian or terrestrial predator during movement over a shallow sand bar in the interim between our tracking trips; a rib bone and some scales were found on a dry sand bar next to the transmitter. The only razorback sucker not used in year 2 was OR-3230, which was not contacted following release; transmitter failure is suspected in this case. since our aerial surveillance extended well beyond the study area and failed to locate this fish. In year 2, we also recontacted 3 razorback suckers (GR-2417, GR-6117, OR-3266) and 1 Colorado squawfish (GR-61 04), which had been tagged during year 1 ; all four fish were equipped with A VM transmitters that had surpassed their 12 to 14- month life expectancy. We no longer received the signals from all four transmitters in March of year 2, and we concluded that these had functioned for about 17 months. During monitoring. these fish appeared to behave nom18l1y. and the data from razorback sucker GR-2417 and Colorado squawfish GR-6104 were included in the year 2 database. Razorback sucker GR-6117 was contacted only by aerial tracking, and was not monitored because the fish was located in a relatively inaccessible area near Mitten Park, while razorback sucker OR-3266 was contacted too infrequently to monitor. In addition to the radiotagged fish described above, 8 northern pike (Esox Jucjus) were surgically implanted with ATS transmitters provided by BaR to assess wintertime interactions with the endangered fish. The results of that aspect at the project are presented in Appendix E. 3.1 Capturing The Fish All fish used in this investigation were captured with a 220-volt DC electrotinding system. powered by either a 4.5-kilowatt EMS Honda generator or a 3.5-kilowatt Humelite generator. The output was controlled by a Coffelt WP-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. Electrofishing was conducted primarily along shorelines and other suitable habitat accessible by boat. The fish were captured from the bow of the boat by one or two netters. All adult Colorado squawfish and razorback suckers were held in live wells for transport to a nearby mobile surgery station lor implanting the 5