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.