Population structure of Rhamdioglanis transfasciatus (Siluriformes, Heptapteridae) in the Boiçucanga Basin, SP Camila Cristina Macedo da Silva, Ursulla Pereira Souza

Abstract

Rhamdioglanis transfasciatusis restricted to coastal streams between Rio de Janeiro and Santa Catarina. The aim of the study was to analyze the population structure of the specie. The fish were collected in the Boicucanga River Basin with electric fishing and measured, weighed and dissected in the laboratory. Differences in body condition regarding sex and degree of repletion were verified by the Kruskal-Wallis test and higher values were obtained in females and individuals with full stomachs. Negative allometry was observed in the species through a regression and the sex ratio calculated by the χ 2 test, not differing from the expected. The hypothesis that females are smaller than males was tested by the t test and the length of first gonadal maturation was estimated by logistic regression.