Age and growth, and distribution as inferred from microchemical analysis of juvenile otoliths, for yellowfin tuna, Thunnus albacares, from the Atlantic Ocean

Three primary spawning grounds for yellowfin tuna have been identified in the Atlantic. Tagging data provides evidence of trans-Atlantic migration; however discrete oceanic movements are unknown. Determination of the contribution of the different nursery grounds to the population will help establish the relative importance of each to the fisheries, allow estimation of rates of mixing, elucidate unclear migratory behaviors, and increase available scientific data on yellowfin in the Atlantic.; Microchemical analysis using solution-based ICP-MS and ICP-AES was conducted on whole otoliths of juvenile yellowfin from the Gulf of Guinea, southeastern Caribbean Sea, and Pacific to establish the utility of using such methodology to delineate natal origin. The study consists of three analysis groups: 'Temporal' assessing inter-annual variation; 'Spatial' assessing variability within a region; and 'Regional' testing for elemental fingerprints of nursery origin. Six elements appeared in consistently reliable concentrations: Mg, Rb, Sr, Ba, K, and Na.; Univariate contrasts indicate elemental differences between sites and years. Fingerprints were examined with discriminant analysis. Clear separation was seen between sample groups in both regional and temporal parts of the study. Moderate separation was observed in spatial samples. Results indicate that elemental fingerprints can be useful delineators of natal origin for yellowfin in the Atlantic.; Age of yellowfin in the Atlantic was estimated using otoliths of fish caught in the Gulf of Guinea and North Carolina. Using the age estimates and corresponding yellowfin fork lengths (FL), the growth curve and parameters were derived with the von Bertalanffy growth function. The resulting growth coefficient (k) is 0.281; theoretical maximum FL, (Linf) 245.5 cm; and theoretical FL of fish at age zero (to), 0.042. This is the first directly estimated age and growth study for yellowfin in the Atlantic that includes fish from the full size range (5.2--179 cm FL). Results do not support the currently accepted two stanza theory of growth. A measure of fecundity was also estimated, with an average value of about 4 million eggs per spawning event. Life history parameters derived from this research can strengthen the population dynamics models currently lacking these important biological data, improving stock assessments used for management.