Laserfiche WebLink
<br />capable of providing continuous information on the movement of fish immediately <br />downstream and immediately upstream of the diversion dam. This technology <br />allowed researchers to determine if a transmitter-tagged Colorado pikeminnow had <br />passed the di version dam. A SRX 400 receiver and three-element di rectional <br />antennae were used to locate fish from boats. An aluminum-jon boat with a 65- <br />horsepower jet drive facilitated up- and downstream travel to monitor movements <br />of transmitter-tagged fish following release. Pertinent data collected for each <br />fish contacted were code, power level, date, time of day, river mile, general <br />habitat type, and surface water temperature. <br /> <br />The numbers of fish by species and age category (sub-adult and adult) were <br />recorded on field data sheets at the end of each sample effort. The unique PIT. <br />tag identification code, serially-numbered Floy tag, or external fin clip was <br />recorded for each fish tagged or marked. Effort was recorded in seconds which <br />was later converted to hours el ectrofi shed. All fish collections were <br />accompanied with detailed information regarding sample number, location, date, <br />time of day, water temperature, and voltage and amperage output of electrofishing <br />equipment. All Colorado pikeminnow that were collected were initially checked <br />for a PIT tag, weighed (g), and measured (total length [mm]). Colorado <br />pikeminnow that had not been previously captured were PIT tagged. All Colorado <br />pikeminnow were released alive. <br /> <br />Fishery data recorded in the field were later stored in the database <br />management system, DBASE IV+, to facilitate access and analyses as well as to <br />provide data compatible with the computer system and format used by the <br />Interagency Standardized Monitoring Program database. <br /> <br />RESULTS AND DISCUSSION <br /> <br />Marking and Recapture <br /> <br />Field work to PIT tag native fishes, floy tag some nonnative fishes (carp <br />and white sucker), and fin clip salmonid fishes (rainbow and brown trout) began <br />3 April 1998. Prior to runoff and the GVIC Diversion Dam being inundated by <br />spring runoff flows, eight different days (7.11 hours of electrofishing) were <br />spent collecting fish to mark between 3 and 27 April (Table 1; Appendix Table <br />B.l.). A total of 744 native fish were PIT tagged and 114 nonnative fish were <br />Floy tagged. Twelve salmonids and 21 hybrid suckers were fin clipped. <br />Unfortunately, only one day (0.77 hours of electrofishing) was dedicated to <br />sampling upstream of the diversion dam for marked fish prior to the diversion dam <br />being overtopped by early spring runoff flows sometime during the week of 26 <br />April to 2 May (Figure 3). None of the 167 native and nonnative fish collected <br />upstream of the diversion dam on that date (27 April) had been marked previously <br />(Table 1; Appendix Table C.l.). <br /> <br />Fish sampling was suspended during runoff. Following spring runoff, <br />electrofishing was resumed 17 July to capture fish downstream of the diversion <br />dam. Initially, between 17 July and 20 August. a total of 384 native fish were <br />PIT tagged, along with 56 nonnative fish that were floy tagged, and three <br />salmonids and 11 hybrid suckers that were fin clipped. Between 24 and 28 August, <br />424 native fish and 13 nonnative fish were fin clipped; another 33 fish were Floy <br /> <br />7 <br />