Commercial catches, reproduction and feeding habits of Raja asterias (Chondrichthyes: Rajidae) in a coastal area of the Tyrrhenian Sea (Italy, northern Mediterranean)

Abstract

         A total of 52 “rapido” (towed toothed beam gears) trawls were monitored in late winter-summer of the 1999-2000 period to assess the R. asterias size structure at this time of higher yields as well as 36 fishing operations performed by “volantina” (trawl nets with fairly high vertical opening) during distinct seasons on the continental shelf off the fishing harbour of Fiumicino (central western Italy) to gain data also for that gear. Daily yields recorded for the only boat locally authorised to use “rapido” nets gave median values of 32.0 individuals and 24.35 kg vs. 2.5 rays and 2.80 kg for trawlers fishing at the same time.
         Comparison of the body sizes at which 50% of the skates had been found mature in our samples (265 gonads examined) showed that most specimens caught by the “rapido” nets were in their juvenile stage. Examination of stomach contents from 129 skates confirmed previous reports that they mainly feed on crustaceans and bony fish and the role of the latter in the diet progressively increases as R. asterias specimens grow older and larger.