7823 - Laserfiche WebLink

Home Browse Search

(0.8-kilometer) reach, such lacking habitat was searched for and sampled in the remaining 4.5 miles (7.2 kilometers) of the section. • Records were kept of effort and the depth velocity and substrate of each sample was recorded. 2. In addition to the quantitative collections outlined above, quali- tative samples were also taken, using a larval dip net. The inves- tigators actively searched out larvae (any habitat) at the site of the seine collections. A sample of these larvae was taken with a dip net. In addition, other samples were taken and accurate records were kept for each collection. 3. The investigators then proceeded to the beginning of the next 5-mile (8-kilometer) section and repeated the process. Samples were collected over three habitats: backwaters, eddies, and shorelines. The number of samples collected per habitat are given below: 1. Backwater (four collections) Deep 2 Shallow 2 2. Eddy (four collections) Deep 2 Shallow 2 3. Shoreline (six collections) Vegetation 2 Gravel/cobble 2 Sand/silt 2 Larval collections were made in late July 1981 and sent to the Larval Fish Laboratory, Colorado State University, for sorting and identification. Beginning in September, YOY collections for larger Colorado squawfish were made using the same sampling design, with the exception that fishes were identified in the field instead of shipped to a contractor and a 1/4-inch (0.6 centimeter) mesh seine was used for all collections. Movements and habitat preferences of young Colorado squawfish Preliminary sampling conducted by the Vernal station in October 1979 indicated that YOY , Colorado squawfish exhibited a diel (24-hour) movement pattern. In 1980, studies were initiated to further examine potential habitat preferences for backwater areas and to explore movement patterns. Sample sites were selected in strata A, C, and F, since young Colorado squawfish were more abundant in those strata in 1979. Each stratum was scheduled for sampling during prerunoff, runoff, and post- runoff river stages to coincide with the standardized sampling program. Each site was sampled for 4 days. Each day was divided into three 8-hour periods; in turn, these 8-hour periods were divided into two 4-hour periods (Table 5). The selected backwater was sampled during each 8-hour period by systematic sampling using a random start. Sampling alternated between the two halves of an 8-hour period. For example, if sampling on 14