8007 - Laserfiche WebLink

Home Browse Search

and 13 July, respectively (Figures 8 and 9). Green sunfish larvae were first collected in late June and early July 1996 (Figure 10 and Appendix 8). In 1995, circular seine collections were made in random locations within the wetland rather than along the shoreline. Age-O carp were collected in 1995 through the entire year while red shiners were the most abundant species collected. Length frequency data indicated that large numbers of age-O fish appeared in Old Charley Wash between the first and third week of August. Reproduction of fathead minnows was also observed with high numbers of age-O fish observed the first week of August. Cylindrical minnow traps used in 1995 were not effective in catching fish; through the entire summer only 16 fish (14 carp and 2 fathead minnows) were captured. In 1996 clover-shaped minnow traps were used instead of seining to sample small and young fishes. Very few fish were collected in the traps until they had been in the wetland for approximately one month (Figure 11). Carp and fathead minnows were the most abundant fish captured in minnow traps. Red shiner was the third most abundant species caught in traps. Length frequency data suggested that both fathead minnow and red shiners reproduced in Old Charley Wash in 1996 with age-O fish being captured during the week of 10 July. In 1995, fyke nets with 13 mm mesh were used to capture larger fish, whereas, in 1996 the fyke used had 6 mm mesh and was capable of capturing both small and larger fishes. As with trammel nets, the composition offyke nets in 1995 were dominated by carp. However, no similar increase in catch/net was observed through time. In general, a greater number of species were collected in fyke nets than trammel nets (8 vs 4 in trammel nets). In 1996, fyke net catches were dominated by three species, fathead minnow, red shiner, and carp (Figure 12). Fathead minnows were most abundant in May, red shiners in June, and carp in the last sample in July. The numbers offish captured increased over time, however, length frequency data suggests that age-O fathead minnows and red shiners did not appear until late June or early July. Therefore, the fathead minnow and red shiner abundance in the May and June were adult fish that accessed the wetland from the river and the increase in carp in fyke nets in 1996 was the result of age-O carp becoming vulnerable to the nets. Very few fish were captured in light traps in open water sample sites in 1995 (Appendix 6). More fish were captured in 1996 when both 2 mm and 6 mm aperture light traps were set in shoreline sites. Five species of fish were collected in light traps, red shiners, fathead minnow, common carp, sand shiner, green sunfish, and speckled dace (Appendix 7). Among these, red shiners and fathead minnows were, by far, the most abundant. Few fish over 25 mm were collected in either 2 mm or 6 mm light traps (Appendix 8). Native fishes represented only a fraction ofthe fishes collected, making up no more than 10.1 % of the composition of any gear type during the study (Table 1). The greatest number of adult native fish collected were in 1995 when seven razorback sucker, four tlannelmouth sucker and one razorback sucker x tlannelmouth sucker hybrid were caught in fyke nets and trammel nets (Appendix 4). One adult razorback sucker and one adult razorback sucker x tlannelmouth sucker Catostomus latipinnis hybrid were collected in a fyke net in 1996. The greatest number of native fish (mostly juveniles) were collected in 1996 when 24 tlannelmouth sucker, 11 roundtail chub Gila robusta, 7 Colorado squawfish Ptychocheilus lucius, 4 speckled dace, 1 razorback sucker, and 1 bluehead sucker C. discobolus were collected in fyke nets. Composition of catches from all gear types are listed by year in Appendices 2,3, and 4. Differences were observed in habitats used by the most abundant fish captured in 1996. Significant differences (0.05) were detected in the numbers of carp and red shiners collected in fyke nets between dates, vegetation 22