Age and Growth of the Pacific Grenadier (Family Macrouridae, Coryphaenoides acrolepsis) with Age Estimate Validation Using an Improved Radiometric Ageing Technique

Longevity estimates for the Pacific grenadier, Coryphaenoides acrolepis, range from 6 to greater than 60 years. Age estimates in this study using growth increments in otolith sections indicate the Pacific grenadier is long-lived. Prior to this study, traditional ageing of this fish was not validated. In this study, the radioactive disequilibria of 210Pb and 226Ra in otolith cores from Pacific grenadier were used to validate age estimates. Accuracy of radiometric ageing using 210Pb: 226Ra disequilibria in otoliths was improved using ion-exchange chromatography and thermal ionization mass spectrometry (TIMS) to measure 226Ra. Because TIMS counts atoms, the accuracy and precision of the technique is superior to a-spectrometric methods. This procedure was applied to otoliths from three other fish species. Results indicate the procedure reduced sample size and processing time, and increased accuracy. Radiometric ages for the Pacific grenadier agree with traditional age estimates and indicate the Pacific grenadier can live at least 56 years