Age structure and multi-model growth estimation of longnose stingray Hypanus guttatus (Dasyatidae: Myliobatoidei) from north-east Brazil
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We collected 729 Hypanus guttatus from the northern coast of the state of Rio Grande do Norte (RN), of which 196 were used to estimate age and growth. Ninety-five were male (12.7 to 57.0 cm disc width; W D ) and 101 were female (13.0 to 88.5 cm W D ); females were significantly larger than males. Cross sections of vertebrae showed band-pairs ranging from 0 to > 14 in females and from 0 to 9 in males. New-borns presented an opaque edge at birth in vertebrae without a birthmark. The average percentage of error (APE; %E) for the entire sample provided evidence that ages were repeatable. The mean monthly marginal increment (I M ) indicates annual band-pair formation from August to November. The annual cycle model for one band-pair deposition provided the best fit to data based on the AIC, with peaks between August and October, similar to that found in the I M analysis, suggesting an annual formation pattern. A multi-model approach that included four models based on the observed mean W D at age indicated a modified von Bertalanffy growth model as the best for describing the species growth: W 0 (W D at birth) = 14.6 cm for both sexes; females W ∞ = 98.61 cm (95% CI = 87.34–114.61 cm); k = 0.112 year −1 (CI = 0.086–0.148 year −1 ); males W ∞ = 60.22 cm (CI = 55.66–65.35 cm); k = 0.219 year −1 (CI = 0.185–0.276 year −1 ). The age-at-maturity in males and females is 5 years and 7 years, respectively. The age composition shows that most (84%) specimens were aged 0 to 2 years. The information provided here is essential for analytical assessments of H. guttatus, which is subject to significant fishing pressure mainly on new-borns and juveniles.