8234 - Laserfiche WebLink

Home Browse Search

234 salmoides and black crappie was attributed to illicit introductions. Of the other native species collected, most declined or increased little in relative abun- dance from previous observations, except Colora- do squawfish. Their appearance was due to the stocking of 17 000 juveniles in April 1988 as part of an experiment to determine if they could be man- aged in a reservoir environment as a sport fish (Trammell 1991, Trammell et al. 1993). Native fishes comprised only 12.1% of fish col- lected in the reservoir in 1989 (Fig. 2) while the re- mainder were non-native species, primarily fathead minnows (Table 2). While percentages of other non-native species were low, black crappie in- creased in relative abundance. Rare in 1988, black crappie composed 3.8% of all fishes collected in the reservoir in 1989. White suckers Catostomus com- mersoni were first recorded in the reservoir in 1989. The only native species composing a notable per- centage in the reservoir was the flannelmouth suck- er (10%); all other native species accounted for less than 1.0% in 1989. Of 246 Colorado squawfish col- lected in the reservoir in 1989, 243 were from 32 000 fingerlings that had been stocked in April 1989. The other three specimens had been stocked in 1988 (Trammell 1991, Trammell et al. 1993). Non-native species in reservoir fish collections increased to 91.1% in 1990 (Fig. 1). Fathead minnow numbers remained high (72.6%), their abundance probably facilitating rapid expansion of black crap- pie whose numbers rose to 17.2% in 1990 (Table 2). Relative abundance of other non-native species was low, although common carp and bluegill were collected in greater numbers than in 1989. Collec- tion of white suckers in 1990 suggested that they had become permanent residents within the drainage. Six native species accounted for only 8.9% of the fishes in 1990 reservoir samples with flannelmouth sucker (5.9%) and roundtail chub (1.9%) being the only species collected in appreciable numbers. Col- orado squawfish collected in 1990 were from the fi- nal plants of juveniles in May (32 000), August (1397), and September (14 200) (Trammell 1991, Trammell et al. 1993). Fish collections above Kenney Reservoir follow- ing impoundment were made only in 1985. While native fishes dominated (79.9%), fathead minnows, particularly in the reservoir inflow, accounted for over 90% (Table 1) of the 23.3% non-native fish component (Fig. 2). Prior to impoundment, fish col- lections above the reservoir basin were dominated by three native species, speckled dace - 17.3%, bluehead sucker - 25.1%, and flannelmouth sucker -32.8%. After impoundment in 1985, native species, pri- marily speckled dace, bluehead sucker and flannel- mouth sucker, comprised 74.7% of fishes collected in the river below Taylor Draw Dam (Table 1, Fig. 2). Fathead minnows, comprising 23.4% of all fishes collected in 1985, greatly outnumbered all other non-native species, none of which exceeded 1%. In 1989 and 1990, fish collections below the dam were roughly 80% non-native and only 20% native. The two native species seemingly most affected follow- ing impoundment were bluehead sucker and speck- led dace. Both species formerly shared dominance among native fishes with flannelmouth sucker and roundtail chub in both pre- and post-impoundment collections below the dam. In 1989-1990, speckled dace composed about 2% of all fishes collected be- low the dam while bluehead sucker accounted for less than 0.5%. Increased captures of Colorado squawfish below the dam in 1989-1990 resulted from escapement of juveniles stocked in the reser- voir (Trammell 1991, Trammell et al. 1993). Non-native red shiner and common carp showed the most notable increases below the dam (Table 1). While fathead minnows composed 20-26% of the fishes collected below the dam in 1989 and 1990, red shiners outnumbered them two-fold in both years becoming the most collected species below the dam. Common carp, scarce in this segment of the White River prior to impoundment, increased no- ticeably in both 1989-1990, particularly the inci- dence of juveniles in seine samples (Trammell 1991). As believed in the case of common carp, increased abundance of black crappie below the dam in 1989- 1990 most likely resulted from increased abundance of these species in the reservoir. These black crap- pie young-of-year and juveniles, were taken in seine or drift net samples (Trammell 1991).