Growth, reproduction and feeding of the tropical squid Ornithoteuthis antillarum (Cephalopoda, Ommastrephidae) from the central-east Atlantic

Abstract

Length composition, age, growth, reproductive biology, feeding and parasites were studied using 432 individuals of the squid Ornithoteuthis antillarum (1.8-138 mm ML) collected in the open waters of the tropical central-east Atlantic. In the region studied, only a small-sized and early-maturing population of O. antillarum occur. Statolith shape, development and microstructure have several peculiar features setting O. antillarum apart of other ommastrephids. Assuming growth increments within statoliths to be daily, maximum age of squids does not exceed 182 days. Growth rates of juveniles and immature squids are high and similar to another fast-growing ommastrephid Sthenoteuthis pteropus, but they decrease considerably with the onset of maturation. Potential fecundity varies from 50,000 to 220,000 oocytes. It is suggested that the squid is a multiple spawner with frequent releases of small-sized (<1,500 eggs) egg masses. O. antillarum can be characterized as a browsing predator, feeding on all available relatively small prey (mainly amphipods as well as larvae and fries of carnivorous fish) in the thermocline and below. O. antillarum is infected mainly by didymozoid trematodes, the intensity of infection being 10-50 times less than in the same-sized S. pteropus. The life cycle of O. antillarum is discussed.