Determinação da idade e crescimento de Astyanax jacuhiensis, (cope, 1894), no Rio Uruguai médio, município de Uruguaiana/RS, Pampa Brasileiro

Abstract

The study was developed on the banks of the Uruguay River in the city of Uruguaiana, RS, Pampa Brazilian. Individuals were collected with dip nets and fishing nets, and later had their individual characteristics and data recorded in the table. For each specimen were recorded: total length (Lt) in centimeters; standard length (Ls); and the total weight (Wt) in grams. Age was determined by reading scales of age rings, and growth assessed by equation Bertalanffy (1938). A total of 243 specimens (133 females and 110 males) was analyzed captured monthly in the Rio medium Uruguay, from May 2014 to April 2015, it was given to the population structure, age and growth of Astyanax jacuhiensis., Classified into 4 classes age. Sex ratio average for the total specimens was 1.50 females for each male. The obtained equations of growth, when adjusted by Von Bertalanffy equation were: L (s) = 13 * [1-exp - 0.279 (t-0.22)] for females to males L (s) = 13 * [1 -exp - 0.262 (T-0.26)] and for the entire population G (s) = 13 * [1-exp - 0.271 (T-0.24)]. And the expressions for the growth in weight are: Wt = 17 * [1-exp - 0.399 (t-0.06)] for females to males Wt = 17 * [1-exp - 0.343 (T-0, 14)] and for the entire population 17 * Wt = [1-exp - 0.373 (T-0.09)]. The total weight ratio - standard length obtained for females and males of Astyanax jacuhieensis was: Wt = 0.0234 * Ls Ls3,15 for females, and Wt = 0.0234 * Ls3,01 for males. The scales are adequate for the study of age and growth, as was observed a correlation between the age and size of the fish.