Efeito do enriquecimento ambiental sobre a morfologia de peixes cultivados

Abstract

Hatchery programs reproduces and cultivates native fishes in captivity for post release into water bodies. This management action is usually applied in Brazil to mitigate impacts caused by dams and reservoirs of hydroelectric plants on fish populations. However there are many controversies regarding the effects of release of hatchery fishes and its effectiveness has never been proven. Much of this inefficiency can be explained by low rates of post-release survival, because fish released are not adapted to the natural environment, but are adapted to captive environment. Tanks have totally different conditions from natural, with a high degree of homogeneity, which results in fish with less variability. Environmental enrichment in hatchery can be proposed as a way to minimize the effects of homogeneity, since incorporates natural designs on captive environment making it more like the natural. From this, the present study evaluated the effect of hatchery enrichment on the morphology of fish. Two types of enrichment were used: structural enrichment, which was provided by the addition of trunks submerged and artificial aquatic plants aimed at increasing environmental complexity, and social enrichment, which was incorporated by addition of a second species in order to increase the degree of ecological interactions. Two species of native and migratory fish were analyzed, Prochilodus lineatus and Brycon orbignyanus. The general aim was to make hatchery conditions closer to those found in nature in order to induce in individuals of both species a morphology more similar to the wild fishes. The results demonstrated that environmental enrichment has a strong effect on the morphology of both species. But each species was differently influenced by enrichment both in relation to morphological traits as in morphological variability. The degree of influence changed depending on the fish age and over time and also depending on the type of enrichment, so the social enrichment had a greater effect than the structural. Overall, the results suggest that environmental enrichment is an effective tool for management in hatchery fish. Regarding morphology can be applied to generate fish with different morphological patterns than conventional. However, more studies should be done to improve the enrichment techniques and better understand how this mechanism works on morphology and development of fish and on the interactions between species