On reproduction and age of the squid Loligo vulgaris from the Saharan Bank (north-west African coast)

Loligo vulgaris (Cephalopoda: Loliginidae) is a commercially important species in the cephalopod trawl fishery in the Saharan Bank (21-26 degrees N). This study on squid in central-east Atlantic waters aims to monthly samples of L. vulgaris were collected from this commercial trawl fishery The maturation pattern for males and females was described from the proportion of immature, maturing and mature animals in the samples and using a maturation index. A range of reproductive indices derived from the morphometrics of the somatic and reproductive systems were also estimated to provide comparative information. The proportion and an abundance index of mature and immature animals in commercial landings in the period 1983-1994 were calculated to provide comparative results of maturity and recruitment respectively. Peaks of mature animals were mainly seen between November and January The summer months exhibited the maximum recruit abundance. Age determinations were also undertaken in order to obtain the hatching peaks and to complete the proposed life cycle of L. vulgaris on the Saharan Bank. A main hatching peak was observed in spring, particularly in in May The age-size relationship suggests differences related to sex and possibly to hatching season. The wide range of size at maturity observed in male L. vulgaris is analysed and discussed. Males showed a seasonal pattern in size at maturity. The dorsal mantle length-body weight relationship and the sex ratio were determined. The sex ratio exhibits a seasonal pattern in relation to body size. Results are compared with information on this species from European waters.