REPRODUCTIVE-BIOLOGY OF WINTER-SPRING SPAWNERS OF ILLEX-ARGENTINUS (CEPHALOPODA, OMMASTREPHIDAE) OFF SOUTHERN BRAZIL

The reproduction and fecundity of winter-spring spawners of the shortf in squid Illex argentinus off southern Brazil (27 degrees S-34 degrees S) were studied in samples from bottom trawl surveys on the outer she lf and upper slope from 1986 to 1992. The mantle length-total weight r elationships were for males: TW = 0.00002456 ML2.974 for females: TW = 0.00004265 ML2.842 and pooled: TW = 0.00005376 ML2.809. Males were he avier than females at the same ML. Fully mature squids were found from July to October. Mantle length and total weight of fully mature males ranged from 188 to 296 mm (mean 252.2 mm) and 195.5 to 611 g (mean 38 2.7 g) and for females from 225 to 356 mm (mean 307.4 mm) and 234 to 7 72 g (mean 558.4 g). Total weight was maximum at full maturity and dec reased in the subsequent stages of both sexes. Mean weight and mean ma jor axis length of ripe oocytes in the oviducts were 0.48 mg (sd = 0.1 0 mg) and 1.27 mm (sd = 0.08 mm), respectively. Total and oviduct mean fecundities, in thousands of oocytes larger than 0.4 mm, in ten fully mature females (294-336 mm ML) were 177.2 (93.0 to 294.3) and 118.4 ( 51.5 to 233.9), respectively. Spawning season in this region seems to be more protracted than in higher latitudes. Our results suggest that a northward migration could take place prior to spawning and that in w inter and spring, southern Brazil may be a major spawning ground of Il lex argentinus that contributes to the local and to the Uruguay and no rtheastern Argentina recruitment.