Multiple management strategies to control selectivity on parrotfishes harvesting

Abstract

Small-scale fisheries are exploiting large numbers of parrotfishes from Brazilian reefs, leading to significant changes in the community structure. Specifically, three now vulnerable species, Scarus trispinosus (Valenciennes, 1840), Sparisoma frondosum (Agassiz, 1831) and Sparisoma axillare (Steindachner, 1878), have been intensively targeted on the Brazilian northeast, although little is known about such fisheries. The vulnerable status of these species has brought about the need to officially regulate their fisheries. Here, the effects of different gear types on the fishing of these three species are analyzed regarding catch composition, size and species selectivity. Landings of gillnet, speargun, and handline fishing were sampled during one year, when information of each fishery operation and size frequencies of fishes caught were recorded. Gillnets are the least selective gear, catching a greater proportion of immature individuals of S. trispinosus. Handline showed the lowest values of capture per unit effort (CPUE) and only caught S. axillare and S. frondosum above the size at first maturity; it did not catch S. trispnosus. Speargun is the only gear that caught a higher proportion of mature individuals of S. trispinosus, which by no means should exempt it from further regulations, as it is important to assure that neither immature nor exceptionally large individuals are removed from the population. Comprehensive parrotfish fishing regulation is urgently needed if the species harvest is to be allowed. Slot size delimitation and gear control are some of the suggested measures to avoid overfishing and changes in life history traits of targeted species.