Comparative analysis of the reproductive activity of Leporinus piau (Characiformes: Anostomidae) in lentic and lotic environments

Aline Virtude Do Nascimento,Nilo Bazzoli,José Enemir Dos Santos,Lucas Marcon,Kleber Biana Santiago,Elizete Rizzo

doi:10.1590/1982-0224-2020-0091

Abstract

Abstract In this study, we determined the main reproductive parameters of piau gordura, Leporinus piau, in two sections of the São Francisco River basin. Between May 2015 and April 2016, a total of 573 specimens were captured from a lentic environment (section 1), the Três Marias Reservoir (TMR), and a lotic environment (section 2), downstream of the TMR at the confluence of the São Francisco River (SFR) with the Abaeté River. Analysis of reproductive activity showed that L. piau from both sections reproduced, but females and males from section 1 exhibited higher total length, body weight, Fulton condition factor, and gonadosomatic index values, as compared to section 2. Sexual dimorphism was evident in the species, with females being larger than males. Moreover, males reached first gonadal maturation at a smaller size than females. The peak maturation/mature stage was observed in November/April for females and males in section 1 and in November/December in section 2, coinciding with high temperatures and precipitation in the region. In both sections of the river, L. piau exhibited the typical characteristics of partial spawning, with a prolonged spawning period, and preferential reproduction in lentic environments.

Highlights

IntroductionIn recent decades, the fish populations have been dwindling due to the construction of hydroelectric dams
The São Francisco River (SFR) is an important source of fish for Brazil
The sex ratio in fish can vary over the life cycle, but it is usually 1:1 in a population (Vazzoler, 1996) as observed in L. piau in section 2 and in other fish species in the SFR (Cruz et al, 1996; Ferreira et al, 1996)

Summary

Introduction

In recent decades, the fish populations have been dwindling due to the construction of hydroelectric dams. The Três Marias Reservoir (TMR) becomes thermally stratified in the summer; the deepest water (hypolimnion) is the coldest and is considered a lentic environment. This cold water is released by the hydroelectric plant (Sato et al, 2005) and subsequently, there are several impacts on fish in the receiving river system. Negative impacts have been detected immediately downstream of several hydroelectric dams in rivers around the world (Donaldson et al, 2008). The SFR is considered to be a lotic environment, which is favorable for fish reproduction (Bazzoli et al, 2019)

Objectives

Methods

Results

Conclusion