Comparative demography of commercially-harvested snappers and an emperor from American Samoa

• Published in: PeerJ (San Francisco, CA) Vol. 6; p. e5069
• Main Authors: Taylor, Brett M, Oyafuso, Zack S, Pardee, Cassandra B, Ochavillo, Domingo, Newman, Stephen J
• Format: Journal Article
• Language: English
• Published: United States PeerJ, Inc 18.06.2018; PeerJ Inc
• Subjects: Age; Aquaculture; Commercial fishing; Demography; Ecology; Emperorfish; Fish; Fisheries and Fish Science; Fisheries management; Fishing; Islands; Lethrinus xanthochilus; Life history; Life span; Lutjanidae; Lutjanus gibbus; Lutjanus rufolineatus; Marine Biology; Mortality; Natural Resource Management; Ontogeny; Otolith; Otoliths; Polynesia; Reproduction; Sexual dimorphism; Snapper; Species; Zoology; American Samoa; Australia; Indo-Pacific region; Pacific Islands; Great Barrier Reef; Fishery; Life history; Reproduction; Otolith; Polynesia; Snapper; Emperorfish
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.5069

The age-based life history of two commercially-important species of snapper (Lutjanidae) and one emperor (Lethrinidae) were characterized from the nearshore fishery of Tutuila, American Samoa. Examination of sagittal otoliths across multiple months and years confirmed the annual deposition of increments and highlighted marked variation in life-history patterns among the three meso-predator species. The humpback red snapper is a medium-bodied gonochoristic species which exhibits striking sexual dimorphism in length-at-age and consequent growth trajectories and has a life span estimated to be at least 27 years. The yellow-lined snapper is a small-bodied gonochore with weak sexual dimorphism, early maturation, and a short life span of at least 12 years. The yellow-lip emperor is a large-bodied species with a moderate life span (estimated to be at least 19 years in this study), rapid initial growth, and a more complex sexual ontogeny likely involving pre- or post-maturational sex change, although this remains unresolved at present. Ratios of natural to fishing mortality indicate a low level of prevailing exploitation for all three species, which is supported by low proportions of immature female length classes captured by the fishery. However, considerable demographic variability among the three species highlights the value of detailed age-based information as a necessary component for informing monitoring efforts and future management decisions.