Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin.

M Camargo,Vj Isaac,T Giarrizzo

doi:10.1590/1519-6984.01914bm

Abstract

This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing.

Highlights

Dams represent one of the most profound human interventions in the hydrological cycle of rivers, causing fundamental impacts through the disruption of physicalchemical and biological processes
The r1 strategist characterised by low survivorship of juveniles and adults, short generation time, variable population densities, and the highest growth rates (K = 0.87.year −1)
Based on the biological parameters estimated for the fishes of the study area on the middle Xingu, there was a clear predominance of r strategist species, characterised by high growth rates (K) and high natural mortality (M), closely associated with early sexual maturation and reduced longevity

Summary

Introduction

Dams represent one of the most profound human interventions in the hydrological cycle of rivers, causing fundamental impacts through the disruption of physicalchemical and biological processes These impacts may benefit the populations of some fish species, but have an adverse effect on the majority of native species, given that few fishes are adapted to both lotic and lentic habitats (McCartney, 2009). In order to mediate the potential effects of damming on natural fish populations, the systematic assessment of existing stocks provides a database for decision-making by the authorities responsible for the management and development of local fisheries (Gulland, 1983). Ferreira (1993), Camargo and Lima Junior (2005) have demonstrated that the population parameters of the same fish species may vary considerably among locations in the Amazon basin In this context, it is essential to understand the biological parameters that define the characteristics of the stocks of the fish species with a given life history

Methods

Results

Conclusion