Comparing sampling strategies for surf-zone fish communities

Abstract

Beach seining is used for capturing surf-zone fishes for scientific or fishery purposes. Sampling gear and different sampling approaches pose difficulties for comparative analyses. We compared parallel tows (PT) and beach hauls (BH) using the same beach seine, observing differences in species number (SPUA = number of species m–2), total and relative abundance (CPUA = number of individuals m–2) and average size. ANOVA and PERMANOVA showed that both the number of species and abundance were significantly different between sampling approaches and seasons, with higher values for BH. Most abundant Umbrina coroides showed significant interactions with higher CPUA for PT in summer and Diplodus argenteus for BH from winter to summer. Harengula clupeola and Trachinotus carolinus showed significant differences between sampling strategy with BH capturing more individuals. Trachinotus carolinus and Sardinella brasiliensis both showed differences between seasons with higher CPUA in the summer and autumn respectively. Results suggest that catch structure and composition differ between sampling strategies, but a seasonal component associated with recruitment of one or more species also influenced the catch. The PT appears to be more effective but time consuming. The BH may be an alternative method, but results may not be comparable.