Comparison between electrofishing and snorkeling surveys to describe fish assemblages in Laurentian streams

Abstract

We evaluated the relative performance of electrofishing and visual surveys (snorkeling) for estimating the abundance of combinations of fish species and size classes in rivers. We also assessed the effect of environmental conditions on potential differences between the results obtained using these two sampling methods. Sampling sites were distributed in the Laurentian region of Québec. Both methods were used while sections were blocked. Three snorkelers swam the river sections upstream while identifying and counting fish of each species and size classes. Three-pass electrofishing was performed in the same sites and abundances were estimated with a maximum likelihood depletion model. Greater abundances of fish were observed by snorkeling than by electrofishing at all sites. Snorkeling species richness was higher or equal to electrofishing richness in, respectively, 60 % and 40 % of sampled sites. Differences in the fish communities observed by both sampling methods were not related to environmental conditions. The results of our work are therefore contrary to that of most published studies that suggested the use of electrofishing over visual surveys. This study highlights that conclusions derived from previous work on sampling gear comparisons may not be generalisable; rather survey methods might benefit from being selected based on fish community composition.

Snorkeling‐Based Fish Stock Assessment by Anglers—A Valuable Method for Managing Recreational Fisheries

“…Our results, therefore, do not concur with those of other authors, who have claimed that the efficiency of snorkeling counts relies heavily on sampling expertise (Chamberland et al. ; Macnaughton et al. ).…”

“…It is often claimed that the efficiency of an assessment relies on the training and expertise of the snorkelers (Chamberland et al. ; Macnaughton et al. ).…”

Detecting Native Freshwater Fishes Using Novel Non-invasive Methods

“…Snorkeling is another visual observation method that has been used to detect and estimate fish densities in small headwater streams (Weyl et al, 2013;Chamberland et al, 2014;Ellender et al, 2018). Snorkel surveys generally outperform seining and electrofishing, except when sampling cryptic species (Brock, 1982;Jordan et al, 2008;Saunders et al, 2011).…”

Coarse woody habitat does not predict largemouth bass young of year mortality during the open-water season

“…anoxia, algal blooms, or large decreases in water level or temperature). We used linetransect snorkel surveys similar to Weidel et al (2007) and Chamberland et al (2013) to quantify relative abundance. We determined through a pilot study in our lakes that electrofishing was not effective at capturing YOY in the spring and early summer, while snorkel surveys allowed for consistent quantification of YOY throughout their first open-water season and did not affect YOY mortality unlike electrofishing and rotenone sampling (Chamberland et al 2013).…”