SUMMARY

This paper examines the correlation between biomass and catchability (q) of yellowfin tuna and the NAO index. Biomass estimates are obtained from a biomass dynamic model fitted to catch and cpue for the period 1950-1999. Several assessment scenarios are investigated. Scenarios are defined by the combination of indices used in the biomass dynamic model and the assumptions made about the variance of each index. Catchability trends are estimated by assuming that q varies according to a random walk with known variance. No significant correlations were observed between the NAO index and either the yellowfin tuna biomass or with the catchability trends of any of the fleets. The only exception was the q for the US longline fleet that was correlated (r <- 0.6) to the NAO index. This correlation is similar in magnitude to the ones detected for bluefin and swordfish. It is likely that these correlations, however, are the product of chance and do not necessarily evidence of forcing of recruitment by oceanographic processes. RÉSUMÉ Le présent document examine la corrélation entre la biomasse et la capturabilité (q) de l=albacore et l=indice NAO. Les estimations de la biomasse proviennent d=un modèle d