Several biological aspects of juvenile specimens of Raja radula were investigated from February to May 2017 in the central Mediterranean Sea. Diet, sex ratio, disc width-weight relationships, and size-frequency distribution were analyzed. Stomach content analysis of 127 collected specimens showed that juveniles of R. radula actively feed on small benthic crustaceans, particularly on amphipods and isopods (Idotea balthica) (%IRI values of 62.74% and 12.39%, respectively). Although the Levin's index value (Bi = 0.44) indicated that juveniles of R. radula are a moderately stenophagous feeders, active mostly on crustaceans, the analysis of the prey-specific (Pi) biomass of the main preys vs. the frequency of their occurrence (%F) showed no clear dominance. The analysis of the sex ratio showed no significant difference in sex distribution. However, there were significant differences in mean size between sexes: females were, on average, larger than males, and also the b value (slope of the curve) of the disc width-weight relationships was higher in females.
|Titolo:||Some biological aspects of juveniles of the rough ray, Raja radula Delaroche, 1809 in Eastern Sicily (central Mediterranean Sea)|
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||1.1 Articolo in rivista|