A method to age octopus was determined through the quantification of growth increments within the stylet structure (highly reduced internal shells). To validate the periodicity of the increments, stylets were analysed from known-age laboratory-raised Octopus pallidus. The animals, which ranged from 3 to 8 months old, were exposed either to a simulated natural or to constant temperature regime. Transverse stylet sections were embedded in thermo-plastic cement and ground until a thin section was achieved. A pre-hatch region and first post-hatch increment was identified in the stylet microstructure. The number of increments, across all ages and temperature treatments, was in remarkably close agreement to age (number of days), clearly demonstrating that stylet increments are deposited daily throughout the lifecycle of O. pallidus. Morphometric analyses of the stylet indicated that increments were laid down regularly during stylet growth and that stylets grew in concert with body size, further supporting daily periodicity. This study successfully validates daily increments in stylets and thus demonstrate a method to age octopus, therefore, potentially having critical implications for future octopus research and the effective management of stocks worldwide. © 2006 Elsevier B.V. All rights reserved.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Zoology
Research Field:	Invertebrate biology
Objective Division:	Animal Production and Animal Primary Products
Objective Group:	Fisheries - wild caught
Objective Field:	Fisheries - wild caught not elsewhere classified
UTAS Author:	Doubleday, ZA (Dr Zoe Doubleday)
UTAS Author:	Semmens, JM (Professor Jayson Semmens)
UTAS Author:	Pecl, GT (Professor Gretta Pecl)
UTAS Author:	Jackson, GD (Dr George Jackson)
ID Code:	42228
Year Published:	2006
Web of Science® Times Cited:	49
Deposited By:	TAFI - Marine Research Laboratory
Deposited On:	2006-08-01
Last Modified:	2009-10-26
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