Israel Hidenburgo Aniceto Cintra

Spatial and temporal variation in the population structure of the halftooth, Hemiodus unimaculatus, in the tucuruí reservoir on the lower tocantins river in eastern Brazilian Amazonia

The present study investigated the spatiotemporal changes in the structure of the population of the halftooth, Hemiodus unimaculatus (Bloch, 1794), in the area upstream from the Tucuruí hydroelectric dam on the Tocantins River, through quarterly samples obtained in 2001, 2003, 2005 and 2007. The variation in the total length and weight of the specimens was analyzed using the Kruskal-Wallis test, with a 5% significance level, while the spatiotemporal variation in population parameters was evaluated using a cluster analysis and SIMPER. A number of changes were found in the population structure of H. unimaculatus, with an increase in population size, a shift in the proportion of juveniles and adults, and alterations of the spatial distribution of the fish. The lack of data on the species and its occurrence in the study area reinforce the need for the development of adequate management measures to avoid overfishing in the future.

Seletividade do matapi nas capturas de Macrobrachium amazonicum no baixo Rio Tocantins, Amazônia, Brasil

The study aimed to determine the selectivity of matapi used in catching Amazon-shrimp, Macrobrachium amazonicum (Heller, 1862), the lower Tocantins River. The fishing was carried out during the rainy season and the dry season of 2013 in three sampling points. Thirty matapis were used for every collection point, with spacing between battens 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm, all with babassu baits. The Kruskal-Wallis test was used to compare mean total length and weight and condition factor of the specimens with 5% error; the weight/length ratios were analyzed by bilateral t test with α=5%; and the selectivity for the curves of selection. The results demonstrated that males are bigger and females are heavier. The weight/length relationship were positively correlated, differed between the sexes (t = - 4.59; p <0.0001), whereas males and females exhibited negative allometric growth. The condition factor was higher in the rainy season. The matapi with spacing of 5 mm of splices is the most suitable for fishing, taking into account the capture of 50% of the adult population and the captured volume.

Avaliação do desembarque de Hemiodus unimaculatus (Bloch, 1794) na área de influência da Usina Hidrelétrica de Tucuruí, Pará, Brasil / Landing assessment of Hemiodus unimaculatus (Bloch, 1794) in the área of the Tucurui Dam, Pará, Brazil

A pesca na area de influencia do reservatorio da Usina Hidreletrica de Tucurui e a principal atividade economica, o que gera alimento, emprego e renda para pescadores da regiao. Neste cenario, a jatuarana-escama-grossa, Hemiodus unimaculatus (Bloch, 1794) se destaca como uma das principais especies desembarcadas. Foram analisadas series temporais de dados de desembarque (do periodo de 2000 a 2008) de jatuarana-escama-grossa. A especie e capturada nas tres subareas de influencia da UHE Tucurui durante o ano todo, sendo a montante responsavel pela maior producao desembarcada. Picos de producao foram verificados nos meses de maio, junho e outubro, na subarea a montante, de maio a agosto no reservatorio e em janeiro e de maio a junho, na subarea a jusante. O principal porto de desembarque de jatuarana-escama-grossa esta localizado no municipio de Itupiranga, que fica a montante da UHE Tucurui. Considerando que a tendencia da producao anual desembarcada esta aumentando continuamente na subarea a montante, e reforcada a necessidade de implementar infraestrutura local, visando essa pescaria e trabalhar regras de ordenamento da pescaria na area.