Data on the diet of species are important for understanding ecosystem
dynamics and are fundamental for the implementation of recent approaches in
stock assessment and consequently for the establishment of more ecological
management measures. In mainland Portugal, as in most European countries,
skates and rays represent an important proportion of commercial landings.
The four main species landed are Raja clavata and Raja brachyura, followed
by Leucoraja naevus and Raja montagui. This paper analyses their diets based
on the examination of stomach contents. Food items were identified to the
lowest identifiable taxon and were further assembled into major taxonomic
groups designated as prey. Intra- and interspecific comparisons were made
according to size and sex. All four species had generalized diets with
differences in prey preference among them. Decapods and bony fish were the
most frequent prey. Furthermore, an ontogenetic dietary shift was evident in
all species at around 45−55 cm total length. Both intra- and interspecific
differences observed seem to be related to size and morphological
characteristics of the species, as well as type of dentition. These
variations allow different species, as well as small and large specimens
from the same species, to exploit a larger diversity of habitats.