FOOD AND FEEDING OF THE SHORT-FILMED SQUID ILLEX-ARGENTINUS (CEPHALOPODA, OMMASTREPHIDAE) OFF SOUTHERN BRAZIL

Diet and feeding habits of the short-finned squid Illex argentinus wer e studied from the analysis of 729 stomachs of juveniles, subadults an d adults caught with trawls on the continental shelf and slope off sou thern Brazil (26 degrees 35'S-34 degrees 31'S) from 1981 to 1992. Food , in different degrees of digestion, was found in 363 stomachs (49.8%) . Feeding activity occurred at day and night and seemed to be most int ense at dusk and early night. The proportion of stomachs with food inc reased with size and sexual maturity. Fish occurred in 43.8%, cephalop ods in 27.5% and crustaceans in 18.7% of the stomachs with food. Ident ified prey included the fish Diaphus dumerilii, Maurolicus muelleri an d Merluccius hubbsi, the cephalopods I. argentinus, Loligo sanpaulensi s, Spirula spirula, Semirossia tenera and Eledone gaucha and the crust aceans Oncaea media and Euphausia sp. The occurrence of fish increased with squid size, but both cephalopods and crustaceans were equally im portant for all sizes. Cannibalism was observed at all sizes. The over all low proportion of stomachs with food, the high rate of cannibalism and the low frequency of occurrence of crustaceans for the juveniles and subadults in all seasons, but particularly in the summer and autum n, may reflect a limited availability of food in the region. If this i s true, the main nursery grounds for the spawners off southern Brazil are likely to be off the Rio de La Plata Front or in the offshore conf luence between the Brazil and Malvinas Currents, where primary and sec ondary production is higher than off southern Brazil. (C) 1997 Elsevie r Science B.V.