Medidas morfométricas na avaliação de pesos e rendimentos corporais de Astyanax lacustris (Lütken, 1875) e Astyanax fasciatus (Cuvier, 1819) (Characiformes, Characidae)

Abstract

The cultivation of native species has become a great opportunity to generate income for fish farmers. In order to obtain an estimate of the productivity, measurements and morphometric reasons, have been studied as auxiliary measures for evaluating weight and yield of the fish. The aim of the study was to verify, by means of the path analysis, the correlation and the direct and indirect effects of the measures and morphometric reasons over body weight and yield of the Astyanax lacustris and Astyanax fasciatus species. A total of 162 lambaris (102 Astyanax lacustris and 60 Astyanax fasciatus) were collected from a stretch of the Rio Grande in Perdões, Minas Gerais (MG), Brazil. Later, the fish were slaughtered, measured and processed for morphometric and yield analysis. The morphometric measurements taken were: standard length (SL), head length (HL), body depth (BD) and body width (BW). Subsequently, we calculated the morphometric reasons and, after processing, the body yields were estimated. Initially, analysis of variance was conducted, followed by the estimation of the direct and indirect effects by means of the path analysis method, considering the slaughter weight, the weight of body parts and bodily income as dependent variables, and the measures and morphometric reasons as explanatory variables. The species differed for variables BD, BW, WVisc, YCarc, YCab, YTron and YVisc. The A. lacustris species presented greater body height and width, carcass and trunk yield, while the A. fasciatus species showed higher head and viscera yield, as well as viscera weight. By means of the path analysis, it became clear that the morphometric measurements can be used to estimate the weight and weight of body components of Astyanax lacustris and Astyanax fasciatus. Regarding weight, carcass weight, trunk weight and viscera weight, variables standard length, height and width of the body were the most crucial. However, for body yields, morphometric measures were not effective in explaining the yield variation between species, given the low setting and weak and insignificant correlations.