Comparison of two methods for sampling a littoral zone fish community

Abstract

We compared two methods for sampling the littoral zone fish community, short-term gillnetting and underwater visual transects, across six habitats classified by water depth and aquatic macrophyte cover. Analyses were performed on species and species life stage data at three numerical scales. The prediction that visual transects would sample more species was supported, as 12 species were observed by visual transects and only nine were captured by gillnets. However, the difference between methods in sampling efficiency was not consistent across habitats. Visual transects sampled more species and life stages in moderate and high cover, whereas gillnets sampled more life stages where cover was minimal. There was a significant correlation between the relative abundance of species determined from visual transects and their relative abundance as assessed by gillnetting across habitats. However, when relative abundance was examined within habitats, only one of the six showed a significant correlation. The ranked abundance of species assessed by visual transects was not significantly correlated with that assessed by gillnetting, either across or within habitats; nor were any of these correlations significant at the life stage level. Overall, our results showed that the two techniques produced a different assessment of the littoral zone fish community, and that underwater visual transects provided broader community coverage.