Validation of yellowedge grouper, Epinephelus flavolimbatus, age using nuclear bomb-produced radiocarbon

TitleValidation of yellowedge grouper, Epinephelus flavolimbatus, age using nuclear bomb-produced radiocarbon
Publication TypeJournal Article
Year of Publication2009
AuthorsCook, M, Fitzhugh, GR, Franks, JS
Date PublishedDEC
Type of ArticleArticle
KeywordsAge determination, Age validation, Gulf of Mexico, Longevity, RADIOCARBON ANALYSIS, Yellowedge grouper

Age validation and estimates of longevity of yellowedge grouper (Epinephelus flavolimbatus) from the Gulf of Mexico (GOM) are needed to inform fishery management decisions. Yellowedge grouper sagittal otoliths (n = 100) were collected, aged using conventional means, and cores were submitted for radiocarbon ((14)C) measurement. Radiocarbon values of yellowedge grouper otoliths were compared to established radiocarbon chronologies in the region to validate the age and ageing methodology of this species. The yellowedge grouper chronology displayed a similar sigmoidal trend as previously published chronologies. In addition to the core analysis, multiple areas on otolith sections from eight specimens were analyzed for Delta(14)C to validate age estimates for fish born prior to the (14)C increase. Our results indicate that yellowedge grouper live longer than previously reported (minimum of 40 years based on radiocarbon measurements). The validated ageing methodology supported an estimated maximum longevity of 85 years and established that yellowedge grouper have the longest lifespan currently known for any species of grouper in the GOM. Results also indicate a depth-age interaction in that material extracted from adult otolith sections assigned to post-bomb dates exhibited lower Delta(14)C values than cores (juvenile material) assigned to the same post-bomb dates. This finding is likely explained by lower (14)C levels reported from water masses at deeper depths (> 100 m) which are inhabited by adults.