Spatial and intraspecific variations in the diet of Plagioscion squamosissimus (Sciaenidae, Perciformes), non-native species, under the influence of cage fish farming

Abstract

The feeding activity of fish is influenced by intrinsic factors, such as morphological and physiological changes throughout their development, as well as by extrinsic factors, such as environmental variations, whether natural or anthropogenic (e.g. cage fish farming systems). Thus, the present work aims to test the hypothesis that cage fish farms promote changes in the diet of the non-native species Plagioscion squamosissimus (Corvina) throughout ontogenetic development. The collection of specimens was carried out with waiting nets in the tank and control areas. Subsequently, the specimens were euthanized, their stomachs removed, fixed in 4% formaldehyde, and preserved in 70% alcohol for further laboratory analysis. Stomach contents will be examined and food items identified to the lowest possible taxonomic level and quantified using the volumetric method. The composition of the diet and its possible differences, between the sample areas and throughout the growth, will be evaluated through PERMANOVA and SIMPER analyses, the trophic niche breadth through PERMDISP, and the relationships between food aspects and the growth of individuals through regression and/or correlation analyses. It is expected that the results of this proposal will contribute to the understanding of the influences of cage fish farming systems on wild ichthyofauna, as well as provide biological information about the target species. Also, provide subsidies for the discussion of the relationship between the influence of cage fish farming and the success in establishing introduced species. (AU)