Otolith microstructure of juvenile fish, the first annulus radius
and pelagic stage duration of icefish Champsocephalus gunnari (Channichthyidae) in the South Georgia area

On the basis of the results of the trawl-acoustic survey in February-March 2002, the microstructure analysis of otoliths of juvenile icefish of 5.5-13.3 cm in length was carried out. Fish studied represent a mixture of two year-classes of 1999-2000 and 2000-2001. The mean width of the daily growth zone in the first 100 days of fish life was 6 ?k at fish length of 4 cm. By the 200th day the daily growth zone was 4.2 ?k at fish length 7.2 cm, by the 300th day – 3.5?k at fish length 11 cm, by the 400th day – 3.1 ?k at fish length of up to 11.8 cm, by the 500th day – 2.8 ?k at fish length of up to 12.5 cm. The resulting age-length ratio can be used in separation of adjacent year-classes during juvenile fish surveys. The length of the young-of- the-year varies within a broad range as a result of prolonged spawning period and by the end of the first summer of fish life approaches 5.5 – 10.4 cm. This corresponds to the age of 120 – 250 days. The length of 1-year-old fish (1+) by the end of the second summer of fish life attains 12.5-13.3 cm, with the age of 477 – 533 days, and the first annulus radius of 0.7 – 1.3 mm. It was revealed that the period of eggs incubation and larvae hatching of the year-class 2000 – 2001 was about 4 months.