Structure of catch sizes and length-weight ratio of native sh in the Abras de Mantequilla wetland, Ecuador

Abstract

The objective of this study was to identify the composition of catches, to describe the size structure and to determine the length-weight ratio of the main species of native sh of commercial interest in the Abras de Mantequilla wetland (AdM). During April to September, 492 shes from the wetland AdM were randomly collected, the total length (Tl) and the total weight (Tw) were measured for each specimen. For the taxonomic identi cation of the species the keys, guides and specialized catalogs were used. The size structure was analyzed by frequency histograms, the mean catch sizes (MCZ) were compared with permitted commercial size (PCS) and mean maturity size (MMS). The length-weight relationship was estimated using the Ricker allometry equation. The most abundant species was Ichthyolephas humeralis followed by Pseudocurimata spp., while Leporinus ecuadoriensis was the least captured species. Rhamdia cinerascens presented a MCZ of 24.81 cm (Tl), inferior to the average size of maturity (25 cm Tl). Ichthyolephas humeralis, Andinoacara rivulatus and Pseudocurimata spp. presented negative allometric growth, while the rest of species have isometric growth. In most sh species recruitment occurred at an optimal age and size in which the sh already contributed with new individuals to the population. It was evidenced that there is a relation between the species with negative allometric growth and its abundance in the catches.