Life history traits of the Narrownose smooth-hound Mustelus schmitti in the San Matías Gulf, Argentina

Abstract

-The life history traits of the Narrownose smoothhound were studied in the San Matías Gulf, northern of Patagonia, Argentina. The age, growth, longevity (Emax) and maturity (TL50% and E50%) were estimated. The age and growth were studied using the vertebral centra reading and the fit to five growth models frequently used in chondrichthyans. The length of the analyzed specimens obtained from commercial fisheries landings ranged between 37 and 89 cm of the total length (TL) for males and between 39 and 106 cm TL for females. Estimated ages ranged between 1 and 15 years for males and between 1 and 21 years for females. Fitted growth models were similar for both sexes without significant differences between sexes. The von Bertalanffy two-phase growth model (two-phase VBGF) for both sexes together was selected as the most adequate considering the both biological and statistical criteria of fit with the following estimated parameters: K= 0.12 year-1; L∞ = 103.12 cm and t0 =-3.56 year (birth length L0 = 35.7cm). Theoretical longevity estimated was 24.4 years. Not significant differences were found between sexes for length at maturity. Both males and females reach maturity at a size of 66.9 cm and at an age of 5.6 years. This study contributes to the knowledge about life history traits in the southern area of the SWA showing that the shark M. schmitti has a moderate growth and the species have high longevity and relatively early average age at maturity within Mustelus.