Demography of the largest and most endangered Brazilian parrotfish, Scarus trispinosus, reveals overfishing

Abstract

Marine Ecology Laboratory, Department of Oceanography and Limnology, Universidade Federal do Rio Grande do Norte, Natal, RN, 59014-002, Brazil 2The Australian Institute of Marine Science, Crawley, WA 6008, Australia 3Fishing Ecology, Management and Economics group, Department of Ecology, Universidade Federal do Rio Grande do Norte, Natal, RN, 59098-970, Brazil Many parrotfishes (Labridae: Scarinae) have life history traits, including late maturation and long lifespans, that make them vulnerable to overfishing. The greenbeak parrotfish Scarus trispinosus is the largest Brazilian endemic parrotfish and has been harvested in reef-associated fisheries along the coast. After a sharp population decline, S. trispinosus is now considered by the IUCN to be an Endangered species. We provide an assessment of age-based and reproductive biology for this species and discuss applications for fisheries management. We sampled 95 individuals from inshore and offshore reefs from Rio Grande do Norte state, northeast Brazil, both obtained from artisanal fishing landings and fishery-independent collections. All sampled specimens were females with fork lengths (FL) ranging from 8.1 to 55.9 cm and ages ranging from 0.3 to 7 yr, with estimated median maturity (L50) of 39.2 cm FL and median age (A50) of 4.2 yr. Size class distributions indicate that the inshore reefs are mostly inhabited by juveniles under L50, whereas the offshore reefs are inhabited by mature individuals, suggesting an ontogenetic habitat shift from inshore to offshore reefs around the timing of maturation. The fishing pressure on this species is concentrated in inshore reefs, therefore mostly on immature individuals, which may be severely affecting the reproductive capacity of this species. This information is useful to guide size-based fisheries management, such as regulating minimum capture size and fishing gears that capture individuals smaller than L50. Managing fisheries of endangered species with late maturity and complex reproductive cycles such as S. trispinosus is imperative to aid recovery.