Estimation of the age and growth in females of Gymnura micrura (Elasmobranchii) captured in Veracruz, Mexico

The Smooth Butterfly ray Gymnura micrura is caught directly and indirectly in the Gulf of Mexico. In order to know their life history, the age and growth parameters were estimated in 96 females captured from October 2015 to September 2016. The age was assigned following conventional protocols comparing the counts between readers and assuming an annual growth band formation. The back-calculation technique was used to complement the missing lengths of the small individuals in the sample. The von Bertalanffy growth model was fitted to both the observed age-length data and with back-calculated data. The size range was 48-89 cm disc width (DW) with estimated age range of 3-11 years. The maximum estimated age was 11 years, corresponding to an individual of 88 cm DW. The relationship between DW and vertebra size is adequately explained by linear regression (r= 0.81, P < 0.05). According to the AIC value (Akaike Information Criteria), including the back-calculated data does not improve the model fit. Estimated parameter to the observed data were DW infinity = 91.05 cm, k= 0.22 years(-1), and DW0 = 21.09 cm. This is the first approximation to know the age of this species, and it is the beginning of understanding its life history and population dynamics.