Age and growth of bluespine unicornfish (Naso unicornis): a half-century life-span for a keystone browser, with a novel approach to bomb radiocarbon dating in the Hawaiian Islands

Andrews, Allen H., Demartini, Eward E., Eble, Jeff A., Taylor, Brett M., Lou, Dong Chun, and Humphreys, Robert L. (2016) Age and growth of bluespine unicornfish (Naso unicornis): a half-century life-span for a keystone browser, with a novel approach to bomb radiocarbon dating in the Hawaiian Islands. Canadian Journal of Fisheries and Aquatic Sciences, 73 (10). pp. 1575-1586.

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Abstract

Bluespine unicornfish (Naso unicornis) from Hawaii were aged to >50 years using cross-sectioned sagittal otoliths. Fish length was a poor indicator of age because of rapid and variable early growth, exemplified by fish aged to be 4 years near maximum length. Growth was deterministic with adult ages decoupled from body length. Otolith mass and thickness were evaluated as proxies for age and both were encouraging; thickness explained more variance but mass was easier to measure. An age estimation protocol was validated through ontogeny using bomb radiocarbon (14C) dating. Use of the postbomb 14C decline period from a regional reference chronology enabled age validation of young fish – a novel approach for the Pacific Ocean. A probabilistic procedure for assigning bomb14C dates (CALIBomb) was used for the first time to determine fish birth years. The age-reading protocol was generally validated, and it was possible to describe length-at-age despite difficulties in counting otolith annuli beyond 30-40 years. Growth curves differed between the sexes, and a four-parameter generalized von Bertalanffy growth function provided the best fit.

Item ID: 49264
Item Type: Article (Research - C1)
ISSN: 1205-7533
Funders: Hawaii Division of Aquatic Resources, Dingell-Johnson Sportfish Restoration (DJSR), National Marine Fisheries Service (NMFS)
Projects and Grants: DJSR award, NMFS Bio-Sampling Initiative
Date Deposited: 08 Jun 2017 05:26
FoR Codes: 06 BIOLOGICAL SCIENCES > 0608 Zoology > 060803 Animal Developmental and Reproductive Biology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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