Bayesian estimation of von Bertalanffy growth parameters for gray triggerfish, <i>Balistes capriscus</i>, incorporating multiple readers and ageing structures

Ageing error can significantly impact growth parameter estimates. However, ageing error is rarely considered as a source of uncertainty as growth is generally estimated from a single age reader's age estimates. Here, we developed a sex-specific Bayesian hierarchical formulation of the von Bertalanffy growth model (VBGM) to estimate gray triggerfish ( Balistes capriscus) growth parameters from multiple ( n = 3) reader age estimates derived from otolith opaque zone counts, a new dorsal spine protocol, and the historical (old) dorsal spine protocol. For all three ageing protocols, estimates of length-at-age were significantly different between sexes, resulting in significantly higher estimates of L ∞ for males compared to females. Estimates of the Brody growth coefficient ( k) from both the otolith and new spine ageing protocols were significantly lower than the old spine protocol estimate. Study results provide a framework for comparing VBGMs, suggest it is most appropriate to fit sex-specific growth models for this species, and suggest stock assessments using ages estimated with the old spine ageing protocol would produce biased results.