Determination of Fish Age Using ²¹⁰Pb: ²²⁶Ra Disequilibrium Methods

Abstract

Previous workers have used disequilibrium in the 210 Pb: 226 Ra ratio in fish otoliths to estimate the age of four teleost species: Hoplostethus atlanticus, Macruronus novaezelandiae, Sebastes diploproa, and Sebastes mentella. We argue that uncontrollable errors due to degassing of intermediate 222 Rn from otoliths, unknown sources and sinks of 210 Pb and 226 Ra, possible changes in the ratio with which these isotopes are accreted to the otolith over the life of the fish, contamination by 210 Po, difficulties in obtaining otolith cores, and the dependence of the estimated radiometric ages on the mass growth-in-time model usually adopted for otoliths can invalidate the application of disequilibrium techniques to fish age estimation.