Abstract
This study investigated the relationships between visual counts of fishes and the catch from gill-nets on rocky reefs in southern New Zealand. Visual censuses were done and then gill-nets of three mesh sizes (2.5″, 3.5″ and 4.5″) were set in the surveyed areas. There were significant differences among habitats in the assemblages of reef fishes. The number and species of fishes caught by the gill-nets had little overlap with those recorded in visual surveys. The standard lengths of fishes caught in gill-nets were significantly larger than those recorded in the visual surveys, primarily because of differences in the species composition of fishes sampled by the two methods. Resident reef fishes, especially labrids, comprised most of the visual surveys, while transient pelagic species and wide-ranging reef fishes made up the largest proportion of the gill-net catch. The three mesh sizes caught different size fractions of fish populations, but all mesh sizes caught fishes larger than those seen in the visual surveys. There was a significant species × mesh size interaction in the number of fishes caught, indicating that some species were more vulnerable to particular mesh sizes. Both the number of fishes and number of species caught declined sequentially with increasing mesh size. This study shows that visual surveys and the more passive gill-netting sample different fractions of fish populations, and that gill-netting is ineffective at targeting individual species in complex reef habitats.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call