210Pb/226Ra Disequilibria in Otoliths of Blue Grenadier, Macruronus novaezelandiae; Problems associated with Radiometric ageing

Abstract

Otoliths from blue grenadier (Macruronus novaezelandiae), which had been aged previously by annuli analysis, were analysed for the naturally occurring radionuclides 210Pb and 226Ra in an attempt to independently verify their age. However, the radiometric technique could not be applied to determine age because the results showed that 226Ra was not incorporated at a constant rate throughout the life of M. novaezelandiae. Uptake of 226Ra was greater in juveniles than in adult fish. This was probably due to the juvenile phase inhabiting inshore/estuarine waters.