Electrofishing distances for sampling fish assemblages in oxbow lakes of the River Rhine

Abstract

Assessment of fish assemblage structure depends on representative sampling. In contrast to lotic water bodies, recommendations for a general study design are sparse for lentic water bodies. Therefore, we evaluated the fish assemblages in different littoral structure types (e.g. macrophytes and riprap stone) and the impact of these structure types on the minimum distance required to obtain samples representative of fish species number in oxbow lakes. Boat-based electrofishing was used at 88 sections, each 200-m long within five oxbow lakes connected to the Upper River Rhine in southwest Germany. Submerged macrophytes and riprap stones were important littoral structures for determining fish community structure. Littoral structure was related to species accumulation, which illustrates the importance of littoral structure to define the minimum length of sampling. Our findings suggest that at least 200-m stretches should be sampled to describe fish assemblages in oxbow lakes.