Faculdade de Ciências Naturais - FACIN/CBREVE

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/4318

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Navegando Faculdade de Ciências Naturais - FACIN/CBREVE por Autor "FREITAS, Tiago Magalhães da Silva"

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    Distribution, feeding and ecomorphology of four species of Auchenipteridae (Teleostei: Siluriformes) in Eastern Amazonia, Brazil
    (Universidade Federal do Pará, 2017) FREITAS, Tiago Magalhães da Silva; MONTAG, Luciano Fogaça de Assis; BARTHEM, Ronaldo Borges
    Fish exhibit morphological, physiological and behavioral specializations which enable them to display diff erent ways to explore the environments and resources. Thus, the aim of this study was to verify how four Auchenipteridae species diff er in the distribution, feeding habits and morphological traits: Auchenipterichthys longimanus (Günther, 1864), Auchenipterus nuchalis (Spix & Agassiz, 1829), Tatia intermedia (Steindachner, 1877) and Trachelyopterus galeatus (Linnaeus, 1766). This study was conducted in rivers and bays of the Anapú Basin, Pará State (Brazil), where these species are abundant. Specimens were collected using gillnets, and after caught the stomachs were removed for the contents analyzes. Eighteen morphometric measurements from ten adult specimens of each species were taken, combined into fi fteen ecomorphological attributes. The species distribution showed that A. longimanus was restricted to rivers, while the others were exclusively caught in the bays. All four species had their diet composed of allochthonous insects, but A. longimanus also exhibited a great frugivorous habit. The most important ecomorphological attributes were relative to the consumption of larger food items (for A. longimanus and T. galeatus) and to the longer swimming capacity (for A. longimanus and T. intermedia). These morphological diff erences and the trophic diversity presented in this study highlighted some important information about how ecomorphological similar species behave and share resources, which may play a signifi cant role on the coexistence of these species in the Anapú Basin.
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    Population and reproductive parameters of the red-tailed catfish, Phractocephalus hemioliopterus (Pimelodidae: Siluriformes), from the Xingu River, Brazil
    (Universidade Federal do Pará, 2019-07) FREITAS, Tiago Magalhães da Silva; MONTAG, Luciano Fogaça de Assis
    A field study of the sex ratio, length-weight ratio, body size at first gonadal maturation, and the breeding season of the red-tailed catfish, Phractocephalus hemioliopterus, was carried out in the region of the middle Xingu River in the eastern Amazon basin. The fish were sampled quarterly from September 2012 to January 2014 using gillnets and long lines. The sex ratio was balanced, and while males and females were similar in standard length, the females were heavier than the males, on average. The males presented negative allometric growth, and the females, isometric growth. The estimated size at first maturity was 77.8 cm. The variation in the gonadosomatic index and the greater frequencies of mature specimens indicated a reproductive peak at the beginning of the high-water (flood) period. As P. hemioliopterus is an important commercial fish, our findings will contribute to the future development of effective conservation and management strategies, such as minimum catch size and a close season that is appropriate for the region. These data will also provide important insights for the evaluation of potential impacts on the biology of this fish resulting from the construction of Belo Monte dam.
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    Predicting size at first sexual maturity from length/weight relationship: a case study with an Amazonian catfish
    (Universidade Federal do Pará, 2016) FREITAS, Tiago Magalhães da Silva; ALMEIDA, Vitor Hudson da Consolação; MONTAG, Luciano Fogaça de Assis; FONTOURA, Nelson Ferreira
    Relationship between length and weight (LWR) is used to describe aspects concerning the life cycle of fish, but does not considers possible changes during the lifetime mainly due to the sexual maturation. Thus, this study aims to identify the size at first maturity of Auchenipterichthys longimanus (Siluriformes: Auchenipteridae) and infer if the reproductive engagement could change growth pattern, concerning the LWR. Estimates of the size at first maturity (L 50 ) were made by visual identification of gonadal development and through the gonadosomatic index (G SI ). L 50 was estimated as 12.5 cm for males and 13.0 cm for females when applied visual identification of gonads development. L 50 estimates increased to 13.05 cm for males and 13.7 cm for females when estimated from G SI values. LWR was adjusted by using a regular power function and through the polyphasic growth model, with proportionality and allometric coefficients changing in a two phases. The results indicate differences in the growth pattern concerning males and females, as well as polyphasic growth. The change in the growth pattern of the polyphasic LWR was estimated at 11.42 cm for males and 12.53 cm for females, suggesting that changes in the growth pattern can sign-out the attainment maturity in this catfish.
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