Effects of Electrofishing Gear Type on Spatial and Temporal Variability in Fish Community Sampling

Abstract

Abstract.-Fish community data collected from 24 major river basins between 1993 and 1998 as part of the U.S. Geological Survey's National Water-Quality Assessment Program were analyzed to assess multiple-reach (three consecutive reaches) and multiple-year (three consecutive years) variability in samples collected at a site. Variability was assessed using the coefficient of variation (CV; SD/mean) of species richness, the Jaccard index (JI), and the percent similarity index (PSI). Data were categorized by three electrofishing sample collection methods: backpack, towed barge, and boat. Overall, multiple-reach CV values were significantly lower than those for multiple years, whereas multiple-reach JI and PSI values were significantly greater than those for multiple years. Multiple-reach and multiple-year CV values did not vary significantly among electrofishing methods, although JI and PSI values were significantly greatest for backpack electrofishing across multiple reaches and multiple years. The absolute difference between mean species richness for multiple-reach samples and mean species richness for multiple-year samples was 0.8 species (9.5% of total species richness) for backpack samples, 1.7 species (10.1%) for towed-barge samples, and 4.5 species (24.4%) for boat-collected samples. Review of boat-collected fish samples indicated that representatives of four taxonomic families-Catostomidae, Centrarchidae, Cyprinidae, and Ictaluridae-were collected at all sites. Of these, catostomids exhibited greater interannual variability than centrarchids, cyprinids, or ictalurids. Caution should be exercised when combining boat-collected fish community data from different years because of relatively high interannual variability, which is primarily due to certain relatively mobile species. Such variability may obscure longer-term trends.

Mesoscale spatial variability of selected aquatic invertebrate community metrics from a minimally impaired stream segment

“…A sample collected from a representative reach (Fitzpatrick et al 1998, Barbour et al 1999) is assumed to be representative of community attributes along a larger stream segment (Rabeni et al 1999, Gregg and Stednick 2000, Meador and McIntyre 2003, even though others have shown that this assumption may be incorrect (Lenz and Rheaume 2000, Brigham and Sadorf 2001, Gebler 2004. Nevertheless, most segment-scale assessments are made from a single sample collected from a representative reach, and most investigators rarely report estimates of uncertainty.…”

Influences of gear type and analytical methodology on fish assemblage characterisations in temperate lakes

“…Per representative unit of effort, species richness in night electric fishing samples was higher than the other gears, supporting results from several studies that night electric fishing captures a high percentage of species present (Meador et al . ), reflects similar richness across multiple years of sampling (Meador & Pollock ) and captures more species than gillnets (Erős et al . ).…”

Multiple hypotheses testing of fish incidence patterns in an urbanized ecosystem

“…Most are a result of limitations with the available data. First, electrofishing is size-selective (Zalewski and Cowx 1990;Meador and McIntyre 2003). Small species (e.g., inland silverside Menidia beryllina, red shiner Cyprinella lutrensis, and western mosquito fish Gambusia affinis), known to occur in Lubbock lakes, were not captured during sampling and consequently were not included in the assessment.…”