7361 - Laserfiche WebLink

Home Browse Search

7 (gradient >2 m/km) sections, where they averaged 10.6 and 21.6% of the electrofishing catch, respectively (Table 1). Freshwater catfishes are not as susceptible to electroshocking collections as are other species, including suckers and minnows (Larimore, 1961; Jacobs and Swink, 1982) and turbid conditions of the study areas prohibited capture of fish not visible at the water surface. Angling with baited hooks in the summer months supported the apparent preference of channel catfish for rocky, high gradient canyon habitats; 34.5 h of fishing in eddy habitats in canyons (lower Yampa River and stratum G, Green River) produced 1.3 catfish/h (n = 46), and 36 h of fishing in eddy habitats in sand and silt-laden sections (strata E and F, average stream gradient 0.2 to 0.4 m/km respectively) produced only 0.5 catfish/h (n = 19). Layher and Maughan (1985) also found that standing stocks of channel catfish increased in higher gradient streams in Kansas. Age and rg owth--Measurement of 604 small channel catfish collected in strata A to F in October 1979 to 1985, indicated that a length of about 80 mm was maximum for the first year of life (Fig. 2). This was confirmed by aging pectoral spine sections taken from 45 small channel catfish (average TL = 53.6 mm, range of 27 to 76 mm) also collected in the Green River, because fish <80 mm TL had no annulus present. Pectoral spine sections from 88% of 361 larger channel catfish collected in the Green and Yampa rivers were given the same age by different technicians and were used for age and growth comparisons. Adjusted back-calculated lengths at consecutive annuli are reported in Table 2. The catfish ranged in length from 26 to 756 mm TL, with respective ages of 0 to 22 years. About 2% of these (n = 8) were >500 mm TL, even though sampling with baits presumably selected for larger fish (Randolph and Clemens, 1976).