Age determination of orange roughy,Hoplostethus atlanticus (Pisces: Trachichthyidae) using210Pb:226Ra disequilibria
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- Fenton, G.E., Short, S.A. & Ritz, D.A. Mar. Biol. (1991) 109: 197. doi:10.1007/BF01319387
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Natural levels of210Pb:226Ra in otoliths of orange roughy,Hoplostethus atlanticus, from south-east Australian waters, were measured to determine fish ages radiometrically. Up to maturity, radiometric age estimates were consistent with a single constant otolith growth rate. Radiometric ages for juveniles were comparable with, but greater than, those obtained in a recent, validated New Zealand study which employed counts of annuli on the surface of otoliths. Beyond maturity, radiometric ages were obtained by modelling with an otolith growth rate set at 45% of the juvenile rate. Radiometric ageing confirms that orange roughy is very slow-growing, with an age at maturity (32 cm standard length, SL) of ~ 32 yr, and is very long-lived, with fish 38 to 40 cm being 77 to 149 yr old. These results have important implications for the management of the fishery.