Early life history of the ocellated icefish, Chionodraco rastrospinosus, off the Antarctic Peninsula

Age, growth and feeding habits of early life stages of Chionodraco rastrospinosus Dewitt & Hureau, the most abundant channichthyid in the larval fish assemblages of the Bransfield Strait, were studied by otolith microincrement counts and stomach content analyses. Individuals measuring 39-69mm standard length were caught in the uppermost depth strata down to 300m from Brabant to Joinville islands along the northern Antarctic Peninsula. The sample consisted of post-larvae and juveniles aged 105-211 days, with a mean growth rate of 0.25mmday-1. Larval size at hatching was estimated to be c. 17.2 mm. Hatching was spread over a relatively long period from August-November. Sagittal otoliths were characterized by a strong check located at 23-52 microincrements of distance from the core, tentatively associated with the onset of first exogenous feeding. The relatively long period during which larvae can rely on yolk reserves and the large size at hatching enable them to utilize a wide size range of prey, as well as cope with occasional food shortages. The stomach contents consisted exclusively of euphausiids (furcilia and adults) and larvae of Pleuragramma antarcticum Boulenger. Based on growth rate, the residence time in pelagic waters of juvenile C. rastrospinosus was estimated to be about a year and a half.