8233 - Laserfiche WebLink

Home Browse Search

In 1995, 23.1 net hours produced six sub-adult Colorado pikeminnow ranging in size from 230-250 mm TL. Flannelmouth sucker dominated the net catch in 1995, however, nonnative channel catfish and common carp were also abundant (Figure 5). Electrofishing, in 1995, for pikeminnow between RK 56.4 and 40.7 (RM 35.0-25.3) resulted in the collection of 16 juveniles/subadults (100-321 mm TL); no adults. Common carp dominated that electrofishing catch and again flannehnouth sucker and channel catfish were abundant. Larval sampling: razorback sucker The first project objective was to review the Larval Fish Laboratory's examination of past collections ofsmall-bodied fish from the lower Green River to determine the presence of any previously unidentified larval or young razorback sucker. This activity was identified in the FY93 recovery program work plan. No larval oryoung-of--year (YOY) razorback suckers were found as reported in subsequent LFL sample processing reports to the Recovery Program (R. Muth, pers. comm.). A total of 333.2 and 458.71arval light trap hours were accumulated in 1994 and 1995, respectively. In 1994, a total of 441arval razorback suckers were collected between the mouth of the San Rafael River (RK 155.0; RM 97.0) and just below Red Wash (RK 152.8; RM 94.9) with the majority of those (n=36, 82.8%) collected on O1 June (Table 2). Collection dates ranged from 17 May to 16 June 1994 and total lengths ranged from 10 mm to 14.2 mm (Figure 6). Only four larval razorback suckers were collected in the lower Green River in 1995, two near the San Rafael confluence (RK 155; RM 97.0), and two near Anderson Bottom (RK 53.6; RM 33.5). Collection dates of these four individuals ranged from 31 May to 30 June, with total lengths ranging from 11.3-12.8 mm (see Table 2 and Figure 6). Four sympatric native species were collected: flannehnouth suckers, bluehead suckers, speckled dace (Rhinichthys osculus) and Gila spp., in decreasing order of abundance. Red shiner was the most abundant species in the 1994 collections, accounting for 53.7% of the total catch (N= 2041). Nonnative cyprinids also dominated the 1995 light trap samples, eventually comprising 80% of the annual total catch (N=1206). Nonnative cyprinid collections generally increased through the sampling period during both years of study. Seine collections were conducted simultaneously with light trapping. All of the 1994 seine collections occurred between RK 156.2-95.3. Nonnative cyprinids comprised 89% of the total catch collected in 20 seine hauls (encompassing a total of 637 m2 of low velocity habitat). Small numbers of flannelmouth sucker, bluehead sucker, speckled dace, channel catfish, common carp, and Gila spp. were captured. The most abundant native fish captured were ninety- fourjuvenile Colorado pikeminnow ranging in size from 40-118 mm TL. In 1995, 41 seine hauls covered 324 m2 between RK 156.2 and 152.2. Nonnative cyprinids accounted for 95% of the catch, along with small numbers of previously mentioned species and two Colorado pikeminnow juveniles (86 and 111 mm TL). Larval sampling: Colorado pikeminnow near Millard Canyon No sampling for larval or YOY Colorado pikeminnow occurred near Millard Canyon in 1994. Specific efforts to locate early life stages of pikeminnow were conducted in 1995 between RK 53.9-40.6 (RM 33.5-25.2). On 28-30 June 19951ow velocity habitats immediately 5