AGE AND GROWTH OF THE SQUID LOLIGO-VULGARIS OFF THE SOUTH COAST OF PORTUGAL, USING STATOLITH ANALYSIS

Age composition and growth rates of the squid Loligo vulgaris (Lamark, 1797) were studied by examination of growth increments within statoli ths of 419 specimens (mantle length, ML, ranging from 32 to 400 mm). T he squid were obtained by monthly sampling from the catches of commerc ial trawls off southern Portugal between March and September, 1993. Th e total number of growth increments in the mounted and ground statolit hs was counted using a semi-automatic image analysis system. ML was si gnificantly correlated with both the statolith length, TSL and the num ber of increments, NI. The female statolith was slightly larger than t he male statolith for the same mantle size. Growth rates of individual s showed high variability with an average estimated at 34.6 mm month(- 1) for males and 33.5 mm month(-1) for females. Growth in length betwe en 70 and 280 days was best described by a power function for both sex es. The growth index of the statolith (TSL/NI) decreased with individu al growth. This result may be related with the onset of sexual maturat ion. L. vulgaris hatched throughout the year with two distinct peaks, in spring which is the main breeding period, and in autumn. The life c ycle of the L. vulgaris population on the south Portuguese shelf was c ompleted in one year.