Canibalismo em peixes.

Abstract

In the beginnings of the 90s the first review about cannibalism in fish was published. Despite several publications later to such revision, the published works deal with more specific features about this behavior, being restricted to few species, regions and periods (e.g. reproduction and migration). Thereby, it is presented an update about cannibalism in fish, based in an extensive literature review, presenting its implications and highlighting areas that merit further research. From such revision two hypotheses were selected and tested, its results are presented in the consecutive sections. Cannibalism frequencies will be determined by (i) feeding resources availability, and (ii) species richness, presenting a secondary effect with latitude, as species richness decreases with increasing latitudes, cannibalism occurrence would be expected to increase with increasing latitudes. Cannibalism was observed for 390 species in 104 families, being common in parental care and carnivorous species. Experimentally, cannibalism was observed to occur only in the total absence of heterospecific prey and seems to be influenced by space segregation and feeding resources availability. Finally, cannibalism was shown to be negatively related with diversity, presenting increasing occurrence number with decreasing diversity. Nevertheless, cannibalism occurrences only presented significant relation with latitude in the northern hemisphere, possibly because the species diversity gradient differs between hemispheres, being more conspicuous in the northern one. Cannibalism seems to be an important factor in structuring populations in the northern hemisphere, especially in higher latitude regions, being influenced by food availability. The influence of cannibalism in determining population and communities dynamic should not be neglected, specially because with increasing human impact in natural environments and, consequently, reduced species richness, this behavior will, probably, be more frequently observed.