JAMARC-INIDEP joint research cruise on Argentine short-finned squid Illex argentinus. January-March 1997.
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The distribution, abundance and population structure of Illex argentinus in relation to the oceanographic conditions during summer 1997, were analyzed as a result of the research cruise carried out by R/V Shinko Maru No.3 on the Argentine shelf (39-50°30'S). Besides, abundance and biological features of Ommastrephes bartrami are analyzed. The main activities carried out during the cruise included jigging operations, tagging (only for I. argentinus) and biological sampling. In addition, meteorological and oceanographic data were collected. A total of 30,2000 individuals were tagged and released. The recapture rate was 0.156. (47 recoveries/30,200 released), considerably higher than that of 1996 (0.030; 4 recoveries/13,191 released). I. argentinus was caught in 46 of the 51 jigging stations on the continental shelf, from 39°S to 49°30'S depths between 50 and 200m. The length distributions of both sexes were generally unimodal but there was a clear evidence that at least two squid spawning groups were present in the surveyed area, judjing from the analysis of the maturity stage distribution. The hatching months, derived from statolith increment readings, ranged from January to August, with most hatching during April-June. O. bartrami was caught in all the stations performed but in a very low number. The CPUE ranged between 0.08 and 0.56 kg/(hs.line), showing that extremely low and similar abundances took place in the whole sampled area, where water surface temperature was between 22.1 and 24.5°C. The 65.78. of the squid sampled were males and the 34.22. females.