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Validation of age and growth estimates using thin otolith sections from the purple wrasse, Notolabrus fucicola

journal contribution
posted on 2023-05-16, 14:46 authored by Graeme EwingGraeme Ewing, Dirk Welsford, Alan JordanAlan Jordan, Colin BuxtonColin Buxton
The age of Notolabrus fucicola from the east and southeast coasts of Tasmania was estimated from counts of opaque (transmitted light) growth zones in thin transverse sections of sagittal otoliths. The position of the first annulus was validated through the otolith radii of known-age juveniles. Marginal increment analysis was performed by examining the growing edge of otoliths over 2 years. This showed that opaque zones were formed annually and were consistently deposited from late September to early December (spring season), which is coincident with annual increases in somatic growth and water temperature during this season. A criterion was developed to ensure accurate age estimation for individuals sampled during the time of year when deposition of opaque material was incomplete or not apparent. The maximum age estimated was 20 years and the relationship between fork length and age was described by the von Bertalanffy growth function (L = 368 mm, K = 0.116 and t0 = -1.87 for males and L = 385.7 mm, K = 0.109 and t0 = -1.96 for females). The clarity of increment structure and rigorous validation protocol that was adopted minimised the risks associated with using marginal increment analysis to validate the periodicity of increment formation and it provided robust age and growth estimates for N. fucicola in Tasmanian waters.

History

Publication title

Marine and Freshwater Research

Volume

54

Issue

8

Pagination

985-993

ISSN

1323-1650

Department/School

Institute for Marine and Antarctic Studies

Publisher

CSIRO Publishing

Place of publication

Australia

Rights statement

© CSIRO 2003

Repository Status

  • Restricted

Socio-economic Objectives

Fisheries - wild caught not elsewhere classified

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