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.