CHANNEL CATFISH POPULATION DYNAMICS, ABUNDANCE ESTIMATES, AND SHORT-TERM TRENDS IN THE PLATTE RIVER, NEBRASKA

Fishing for channel catfish (Ictalurus punctatus) is popular in Nebraska and channel catfish are the most sought after fish species in the Platte River. Anglers on the Platte River are also harvest oriented. Little is known about the effects anglers have on channel catfish population dynamics in the lower Platte River. The goal of this study was to determine if there were effects of angling on channel catfish at two high use fishing areas in the lower Platte River. My first objective was to evaluate differences in relative abundance, size structure, condition, age structure, growth, and mortality between two high use areas (near Fremont and Louisville, NE). I also used a robust design capture-mark-recapture study to estimate density and abundance of channel catfish \u3e 200 mm within a 10-km stretch of the Platte River at each sampling site. The second objective was to assess the 5 year standardized monitoring data for spatial and temporal differences in relative abundance, size structure, condition, age structure, growth, and mortality across two river reaches and three river segments. Channel catfish at Fremont displayed lower size structure, slower growth, and were more abundant compared to channel catfish at Louisville. Population characteristics displayed considerable variation throughout the Platte River in the last five years. However, channel catfish sampled between the Loup River Power Canal and the Elkhorn River confluence were more abundant, grew slower, and had a lower size structure compared to channel catfish above and below that segment. Key factors influencing differences in channel catfish population characteristics may be due to hydrology (e.g., flow modifications caused by the Loup River Power Canal, irrigation withdrawals, and precipitation amounts) and the resulting changes to other abiotic factors (e.g., water temperature extremes, ice flow), angler exploitation, predation, habitat characteristics, and tributary inflows. Adviser: Mark A. Peg