Another New Zealand centenarian: age validation of black cardinalfish (Epigonus telescopus) using lead–radium and bomb radiocarbon dating

Abstract

Black cardinalfish (Epigonus telescopus, Apogonidae) is an important component of deepsea commercial fishing activity in the New Zealand region. It is estimated to live longer than 100 years on the basis of counts of unvalidated annual growth zones in otoliths. Age-validation procedures for long-lived fishes are often one of the following two techniques: (1) lead–radium disequilibria, which uses the natural decay of radium-226 into lead-210 as a natural clock; or (2) bomb radiocarbon (Δ14C) dating, which relies on the marine signal created by nuclear testing. The high estimated lifespan, as well as the large size of the otolith core region, make E. telescopus an excellent candidate for a combined application of these two independent age-validation techniques. The lead–radium dating using otolith cores indicated that growth-zone counts less than ~60 years were consistent with radiometric ages, whereas higher counts appeared to be under-estimates. There was 95% confidence that maximum age was at least 95 years. The validation indicated that fish aged over 60 years tended to be under-aged by up to 30%. The bomb radiocarbon levels in otolith cores supported age estimates up to ~40 years made from zone counts, and by inference from the zone counts validated with lead–radium dating, longevity exceeds 100 years.