The ecology of loliginid squid in shallow waters around Santa Catarina Island, southern Brazil

The population structure, environmental influences, and diet of three loliginid squid species, Loligo plei Blainville, 1823, Loligo sanpaulensis Brakoniecki, 1984, and Lolliguncula brevis (Blainville, 1823) were studied in coastal shallow waters (< 20 m) around Santa Catarina Island, southern Brazil, in three austral summers, between 1999 and 2001. Samples were obtained mostly by hand-jigging at Pântano do Sul Bight (27°47′18″S; 48°31′07″w) in 13 bi-weekly 24-hr sampling trips which also included the collection of oceanographic data. Most Loligo spp. were mature, although the inverse was found for L. brevis. Sex ratio was close to 1:1 in L. plei but biased for the other loliginids. Loligo plei occurred more often when the water column was thermally stratified. In contrast, the highest number of large L. sanpaulensis occurred in less saline water, although small squid were associated with upwelled water. Lolliguncula brevis were associated with warm and stable conditions. Examination of stomach contents revealed that Loligo spp. had similar food habits, preying upon fish, planktonic crustaceans, polychaetes, and other loliginids. Results indicate that coastal areas are used as feeding grounds by mature Loligo squid, some of which were reproductively active. It is hypothesized that coastal L. plei could be distinct from offshore individuals due to their larger sizes and different size-at-maturity.