Impactos de pisciculturas em tanques-rede sobre a ictiofauna da ...

Abstract
Sistemas de pisciculturas em tanques-rede modificando a alimentação de peixes nativos
Autor: Igor Paiva Ramos
Historically, Brazilian ichthyofauna of large rivers has been subjected to anthropogenic
interference, such as impoundments. Consequently, fish farming systems in cages are a
currently new source of impact upon aquatic ecosystem. Characterizing the impacts of
freshwater fish farms on the feeding of five species of Neotropical freshwater fish, associated
with these activities, was the objective of this study. Specimens of Astyanax altiparanae,
Galeocharax knerii, Iheringicthys labrosus, Pimelodus maculatus and Plagioscion
squamosissimus were sampled in areas around the two systems of fish farming in cages (CF),
and two control areas (CT) without the influence of this activity. The results show that there
were significant changes in the diet of trophic generalist species (A. altiparanae, P. maculatus
and I. labrosus) with consequent increase in condition factor values of such species in tank
areas. Trophic specialist species, such as the carnivorous fish species G. knerii and P.
squamosissimus, showed small differences between CF and CT areas regarding the diet, and
showed no differences in other analyses performed. It is concluded that fish farms in cages
affect the natural diet of trophic generalists fish species, with a direct effect on nutritional
status (condition factor), and food wastes is one of the main items consumed by this trophic
guild. The results indicate that these species are responsible for recycling a great portion of
organic matter transferred by this type of activity, which along with local fisheries activities
contribute to mitigate associated processes of eutrophication.
Key words: diet, condition factor, niche breadth, aggregate ichthyofauna, native fish
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