Age estimation and validation for South Pacific albacore Thunnus alalunga

Farley, J.H., Williams, A.J., Clear, N.P., Davies, C.R., and Nicol, S.J. (2013) Age estimation and validation for South Pacific albacore Thunnus alalunga. Journal of Fish Biology, 82 (5). pp. 1523-1544.

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Abstract

Validated estimates of age are presented for albacore Thunnus alalunga, sampled from a large part of the south-western Pacific Ocean, based on counts of annual opaque growth zones from transverse sections of otoliths. Counts of daily increments were used to estimate the location of the first opaque growth zone, which was completed before the first assumed birthday. The periodicity of opaque zones was estimated by marginal increment analysis and an oxytetracycline mark–recapture experiment. Both validation methods indicated that opaque zones formed over the austral summer and were completed by autumn to winter (April to August). The direct comparison of age estimates obtained from otoliths and dorsal-fin spines of the same fish indicated bias, which was assumed to be due to poor increment clarity and resorption of early growth zones in spines, resulting in imprecise age estimates. As such, age estimates from otoliths are considered to be more accurate than those from spines for T. alalunga. This is consistent with results for a growing number of tropical and temperate tuna Thunnini species. It is recommend that validated counts of annual growth zones from sectioned otoliths is used as the preferred method for estimating age-based parameters for assessment and management advice for these important stocks.

Item ID: 31947
Item Type: Article (Research - C1)
ISSN: 1095-8649
Keywords: ageing protocols; annual; marginal increment analysis; otoliths; spines
Funders: CSIRO Wealth from Oceans Flagship, Fisheries Research and Development Corporation (FRDC), 9th European Union Development Fund, Western and Central Pacific Fisheries Commission
Projects and Grants: EUDF SCIFISH project
Date Deposited: 07 Apr 2014 00:45
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070402 Aquatic Ecosystem Studies and Stock Assessment @ 100%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830207 Wild Caught Tuna @ 100%
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