Environmental Variation and Habitat Use Affect Blue Catfish Low‐Frequency Electrofishing Catch Rates

Abstract

The Blue Catfish Ictalurus furcatus is a popular sport fish in its native range and a prolific invasive species in its nonnative range. Low‐frequency electrofishing (LFE) is effective for sampling Blue Catfish, and development of standardized LFE protocols for sampling Blue Catfish is critical for monitoring and management of their populations. However, standardized sampling for Blue Catfish can be difficult because their habitat use is variable among seasons and habitats, and LFE is affected by a suite of abiotic factors. To quantify this variation, our objectives were to determine how Blue Catfish LFE catch (1) differs during spring and summer sampling seasons, (2) is affected by environmental variables, and (3) relates to their habitat use. To do so, we conducted a telemetry study and systematic random LFE sampling in Lake Dardanelle, Arkansas, in the spring and summer of 2016. We compared the numbers, capture rates, and size structure (proportional size distribution index of quality‐size fish) of telemetry‐located and LFE‐captured Blue Catfish in distinct habitats and found that habitat use was heterogeneous but capture rates were proportional to habitat use. Blue Catfish catch increased with conductivity and decreased with flow velocity; catch also differed among habitat types, among reservoir zones, and between seasons (spring/summer). Understanding how spatiotemporal differences in habitat use contextualize the effects of LFE catch will improve sampling protocols for Blue Catfish.

Evaluating Single‐ Versus Chase‐Boat Low‐Frequency Electrofishing for Assessing Flathead Catfish and Blue Catfish Populations in a Large River

“…Previous evaluations of low‐frequency electrofishing have been limited to either Flathead Catfish (e.g., Cunningham 2004) or Blue Catfish (e.g., Bodine and Shoup 2010; Moran et al. 2021) populations rather than both species together. In the Ohio River and other large river systems and reservoirs, Blue Catfish and Flathead Catfish cooccur, and populations of both species are assessed by fisheries management agencies simultaneously using low‐frequency electrofishing (e.g., KDFWR 2020; Rachels and Fisk 2021).…”

“…and environmental variables, such as temperature and discharge (e.g., Daugherty and Sutton 2005; Moran et al. 2021), are unknown, particularly for Flathead Catfish, and hinder the interpretation of low‐frequency electrofishing data. Currently, evaluations of low‐frequency electrofishing methods have focused on reservoir catfish populations (e.g., Cunningham 2004; Bodine and Shoup 2010; Moran and Stoeckel 2021), whereas sampling in large rivers has received far less attention despite the importance of riverine catfish fisheries (Graham 1999).…”