A Comparison of Point Abundance and Continuous Sampling by Electrofishing for Age-0 Fish in a Channelized Lowland River

Abstract

Because of its efficiency as a sampling method, electrofishing of age-0 fish is often used to assess natural reproduction in rivers. However, little is known about the relative tradeoffs of accuracy and efficiency of different electrofishing methods. For monitoring purposes, it is important to find a method that accurately estimates age-0 fish assemblages and that is relatively quick and inexpensive. Though some studies have compared the suitability of different methods for addressing particular research or management questions, to our knowledge this is the first study comparing two different electrofishing sampling strategies: point abundance and continuous. We compared time effectiveness and accuracy of estimating age-0 fish assemblages obtained by point abundance and continuous electrofishing on the lowland Morava River (Danube River basin, Czech Republic). Forty sites were surveyed by each strategy along two types of shoreline: submerged vegetation and boulder bank. Both strategies yielded similar qualitative data (species richness, relative proportion of species, and size structure) along each shoreline type. Point abundance sampling required a shorter amount of survey time than did continuous sampling. We conclude that point abundance sampling is the more suitable method for routine sampling of age-0 fish assemblages in lowland rivers.