Date of this Version
The channel catfish, Ictalurus punctatus, is an important component of the Platte River fishery, representing the most abundant and sought-after sport fish. However, little is known concerning the size structure and growth characteristics of this population. We collected channel catfish from seven sites along the lower Platte River from 1988 to 1991, using a combination of hoop nets, boat electrofishing, and angler tournament harvests. Pectoral spines were removed from a subsample of catfish collected, sectioned, and aged for determination of backcalculated growth. Proportional Stock Density (PSD) calculated from hoop net and electrofishing collections averaged 7.2% and ranged from 4.0 to 10.7%, compared to PSD from angler harvests which averaged 66.6% and ranged from 53.8 to 79.3%. Incremental Relative Stock Density (RSD) analysis showed that anglers were harvesting more fish in the RSD Q-P category, while our sampling indicated that most stock size fish were in the RSD S-Q category. There were no consistent differences in mean monthly and annual K values between sexes of catfish both within or between sampling locations. Backcalculated estimates of the mean total length of age 1 channel catfish averaged 84 mm and ranged from 69 mm in spring 1989 to 101 mm for spring 1991. Mean annual growth increments for the next four years declined steadily from 65 mm between ages 1 and 2 to 54 mm, 50 mm, and 47 mm between ages 2 and 3, 3 and 4 and 4 and 5 respectively. It took four to six years for channel catfish to reach 300 mm in the Platte River. No consistent differences in mean lengths at age between locations were evident. The channel catfish population of the lower Platte River exhibits a longitudinally-uniform pattern of slow growth, with an age structure skewed towards younger age groups.