Biologia de Hoplias malabaricus (Bloch, 1794) (Characiformes, Erythrinidae) na Represa de Capim Branco I, Rio Araguari, MG

Abstract

The biology of Hoplias malabaricus, with regard to population structure, growth, reproduction and feeding were studied in a section of the newly reservoir formed by Usina Capim Branco I, Araguari River, Brazil. The fieldwork took place between July 2006 and June 2007, and 114 individuals were captured. The species presence was constant in nearly every month, with the exception of the months of September, October and November, 2006, when that number was more abundant. The distributions of sizes revealed differences between the sexes with a predominance of females in the last class (4, 5 and 6), which can be attributed to the strategies related to reproduction. The sex ratio differed significantly from 1:1, occurring the predominance of females. Differences were also found in the proportion of young and adults individuals, showing that there was a prevalence of adults ones in reproductive age and young ones in the post-reproductive period. The factor of condition reduced during the reproductive period, and tended to increase in the following months. The relation weight-length has indicated an allometric positive growth to that species, showing that males and females have different growth. The growth study revealed scales containing from one to seven rings which are formed annually and during the summer. The age of first gonadal maturation occurs between the first and second years of age. The item most frequently found in the examined stomachs shown the species is insectivorous when young and piscivorous when adult. The high frequency of empty stomachs indicate the sedentary habit and resistance to fasting. The data indicated that the reproductive period occurs between the months of August and January, coinciding with the rainy season in the region. The raised informations indicate the importance of understanding the biology of the species for its maintenance in the studied area and also reinforce the importance of studies about Capim Branco I reservoir, necessary to maintain the life cycle of the studied species.