9781888569155-ch6
Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals
Application of Radiometric Age Determination to Three Long-Lived Fishes Using 210Pb:226Ra Disequilibria in Calcified Structures: A Review
Erica J. Burton, Allen H. Andrews, Kenneth H. Coale, and Gregor M. Cailliet
doi: https://doi.org/10.47886/9781888569155.ch6
Abstract. —Radiometric aging of fishes is a recently developed technique using the disequilibria of 210 Pb:226 Ra in calcified structures to determine age. It has been applied successfully to several fish species, but certain limitations have made improvements desirable. Because 226 Ra can be measured directly by counting atoms using isotope-dilution thermal ionization mass spectrometry (TIMS), a new ion-exchange separation technique was developed to isolate small quantities of radium from calcified structures for TIMS determination. The advantages of this new technique are reduced sample mass and processing time, and greater accuracy and precision of radium quantification. We applied this technique to calcified structures from three fish species: otolith cores of Pacific grenadier Coryphaenoides acrolepis and tarpon Megalops atlanticus, and pectoral fin ray cores of Atlantic sturgeon Acipenser oxyrinchus. Annulus-derived age estimates for C. acrolepis were accurate with a confirmed longevity of at least 48 years. Although annulus-derived ages for M. atlanticus were inconsistent with radiometric ages, radiometric aging confirmed that tarpon are longlived; females may exceed 82 years. Radiometric age could not be determined for A. oxyrinchus because 210 Pb activities were greater than could be supported by ingrowth from 226 Ra decay. In this paper we discuss the application and limitations of this technique and its relevance to fisheries management.
