AGE, GROWTH AND MATURATION OF THE SQUID MARTIALIA-HYADESI (CEPHALOPODA, OMMASTREPHIDAE) IN THE SOUTH-WEST ATLANTIC

The statolith microstructure was studied in 142 females (mantle length , ML, ranging from 77-402 mm) and 119 males (72-328 mm ML) of Martiali a hyadesi caught on the Patagonian and Falkland shelves and at the Ant arctic Polar Frontal Zone between 1989-94. The statolith microstructur e dark zone in this species, contains narrower and more numerous growt h increments than the dark zones of other ommastrephid squids. Assumin g daily production of putative growth increments within statoliths mal es live up to 12 months, and females live up to 13 months. It is likel y that the life cycle lasts c. I yr, but immature squids with ages >33 0-340 d suggest that a part of M. hyadesi populations could have life span >1 yr. Growth in length was best described by the Gompertz functi on, whereas growth in weight was best described by the logistic functi on. M. hyadesi is characterized by slow juvenile growth (<100 mm ML), fast growth of immature squids and a sharp decrease in growth rates du ring maturation. M. hyadesi mature later (at ages >270 d) than other t emperate ommastrephids, but maturation is rather rapid (2-3 months). I n the south-west Atlantic, M. hyadesi hatch throughout the year.