Gear‐Specific Population Demographics of Channel Catfish in a Large Midwestern River

Abstract

Various gear types have been used to sample populations of channel catfish Ictalurus punctatus in lotic systems. However, these gears produce different population characteristics (i.e., recruitment, growth, and mortality). We compared the population demographics of channel catfish in the Wabash River, Indiana, sampled with baited 25‐ and 32‐mm‐bar mesh hoop nets and three‐phase alternating current (AC) electrofishing. Based on catch per unit effort, the relative abundance of channel catfish sampled with 32‐mm hoop nets was lower than that of fish sampled with 25‐mm hoop nets and AC electrofishing. Each gear type also resulted in a different length frequency, mean length increasing progressively in sampling with 25‐mm hoop nets, 32‐mm hoop nets, and AC electrofishing. Similarly, age‐frequency distributions differed among gears. The 25‐mm hoop nets biased the age structure toward younger individuals (mean age = 2.5), whereas both 32‐mm hoop nets (mean age = 4.0) and AC electrofishing (mean age = 5.8) included older fish. Catch‐curve analysis generated different mortality rates for the three gear types, the mortality rate being highest (50%) in fish sampled with 25‐mm hoop nets. Gear‐specific size and age structures led to differences in von Bertalanffy statistics among the 25‐mm hoop nets and AC electrofishing, while the results for 32‐mm hoop nets were uninterpretable. Because the different gears led to conflicting parameter estimates, management practices based on sampling with single gears may be contradictory. Given the differences in gear selectivity, biologists need to approach management cautiously until calibration to the true size and age structure is conducted.

Evaluation of Unbaited Hoop Nets for Simultaneously Assessing Channel Catfish and Flathead Catfish populations in the Minnesota River

“…Studies that used single baited hoop nets to sample Channel Catfish in lotic systems generally have reported catch rates similar to those observed in this study (i.e., 1.5–2.6 fish/net‐night; Quist and Guy ; Colombo et al. ; Barada and Pegg ). For Minnesota River Flathead Catfish, Stauffer and Koenen () reported mean low‐frequency electrofishing catch rates of 27.4 fish/h, but few were larger than 600 mm.…”

Capture Efficiency and Size Selectivity of Channel Catfish and Blue Catfish Sampling Gears

“…(see reviews by Vokoun et al 1997 and Vokoun and Rabeni 1999); however, capture efficiency and size selectivity of most catfish sampling gears are unknown. Colombo et al (2008) reported that different gear types (e.g., hoop nets and electrofishing) used to collect channel catfish I. punctatus produced conflicting population parameter estimates, identifying the need to determine biases associated with each gear. In a 2006 survey by the Catfish Management Technical Committee of the Southern Division of the American Fisheries Society, 61% of the biologists surveyed indicated a need for information regarding sampling gear bias and gear efficiency (Brown 2007).…”

Assessment of a channel catfish population in a large open river system

“…For instance, annual survival in the Red River, Manitoba was 95% (multi‐state model survival parameter; Siddons, ), 85% in the Ottawa River system (catch curve; Haxton & Punt, ) and 77% in the Powder River system (catch curve; Gerhardt & Hubert, ). Conversely, annual survival estimates from a commercially exploited population of channel catfish in the Wabash River, Indiana ranged from 50% to 72% (catch curve; Colombo, Phelps, Garvey, Heidinger & Stefanavage, ). A combination of factors is likely responsible for the lower survival estimates in this study compared to previously published estimates.…”

“…Repeated sampling with standardised gears was relied on to provide information on channel catfish population characteristics. Hoopnets have been shown to be effective for assessing size structure for channel catfish populations in rivers (Buckmeier & Schlechte, ); however, different configurations and gear types can influence population variables (Colombo, Phelps, Garvey, Heidinger & Stefanavage, ). Electric fishing was employed to potentially sample larger channel catfish not susceptible to hoop nets configured in this study; however, length frequency distributions were similar between gears.…”