Laser ablation–accelerator mass spectrometry reveals complete bomb 14C signal in an otolith with confirmation of 60-year longevity for red snapper (Lutjanus campechanus)

Abstract

Bomb-produced 14C has been used to make valid estimates of age for various marine organisms for 25 years, but fish ages that lead to birth years earlier than the period of increase in 14C lose their time specificity. As a result, bomb 14C dating is limited to a minimum age from the last year of prebomb levels because the temporal variation in 14C in the marine surface layer is negligible for decades before c. 1958. The longevity of red snapper (Lutjanus campechanus) in the Gulf of Mexico remains unresolved despite various forms of support for ages near 50–60 years. Although the age and growth of red snapper have been verified or validated to a limited extent, some scepticism remains about longevity estimates that exceed 30 years. In this study, red snapper otoliths were analysed for 14C using a novel laser ablation–accelerator mass spectrometry technique to provide a continuous record of 14C uptake. This approach provided a basis for age validation that extends beyond the normal limits of bomb 14C dating with confirmation of a 60-year longevity for red snapper in the Gulf of Mexico.