Biological feature of an oceanic squid, Sthenoteuthis oualaniensis in the South China Sea, Area III: Western Philippines

Several species of oceanic squids are believed to occur in the South China Sea, especially off the west coast of the Philippines. Sthenoteuthis oualaniensis was one of the species that dominated the catch during the research survey off western Philippines in April to May 1998. Preliminary study was carried out on some biological features of Sthenoteuthis oualaniensis, particularly on maturity pattern, sex ratio and stomach content. There was a similarity in maturity pattern throughout the study areas with the same proportion of mature and immature squids. In all stations, the female squids outnumbered the male and the size of the female was general bigger than the male squids. ML50% of female was estimated to be at 175 mm while range of mature female was between 110 - 240 mm. Fish and cephalopods were the most frequently occurring prey taxa found in the diet of Sthenoteuthis oualaniensis, contributing between 37% - 46% and 30% - 43% respectively. Identification of prey taxa especially to species level was strictly limited, due to lack of proper references and understanding of the nature of fish species composition within the study areas. Results discussed in this paper may serve as early information for future biological study on S. oualaniensis.