Sampling Channel Catfish with Tandem Hoop Nets in Small Impoundments

Abstract

Because populations of channel catfish Ictalurus punctatus have been difficult to sample in small impoundments. we determined whether tandem hoop net series (three nets tied in series and baited with cheese) fished for 3 d could effectively sample these populations, In 2000 we compared seasonal catch rates (catch per unit effort [CPUE], defined as the number of fish caught per series) and length frequencies (total length [TL]: mm) of channel catfish captured with two types of tandem series (long versus short bridles) and monitored the mortality of channel catfish along with the CPUE and mortality of bycatch in five lakes, Mean CPUE ranged from 12 to 194 fish/series for channel catfish and front 5 to 101 fish/series for bycatch among series types. takes, and sampling periods. Mean CPUE for channel catfish and bycatch was similar between series types and did not consistently vary with sampling period. Length frequencies of channel catfish were usually similar between series types. Mortality was low for both channel catfish (0.3% of total catch) and bycatch (8%). In 2001, using short-bridled series, we assessed gear size bias in one lake; sampled 66 lakes that are stocked annually with channel catfish fingerlings at rates of 12, 37, or 74/ha and estimated the sample sizes required for precise estimates of mean CPUE and accurate estimates of size structure. Hoop nets failed to capture channel catfish less than 250 mm TL in proportion to their abundance, Mean CPUE among 02 lakes ranged from 0,5 to 369,7 channel catfish/series and increased with stocking rate. Four lakes were excluded because of the high catch and mortality of turtles. Mean TL ranged from 276 to 403 turn among the lakes and decreased with stocking rate. For moderate precision (coefficient of variation [100-SE/mean] = 0.2) of mean CPUE, from 12 to nearly 50 series were required. and length measurements from 300 fish were necessary for accurate assessments of size structure, Tandem hoop netting provided adequate samples of channel catfish in most small impoundments, hut obtaining precise estimates of CPUE may be difficult; moreover, turtle mortality can lie problematic in some lakes.