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

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    Número de documento:
    WG-FSA-03/75 Rev. 1
    L.V. Shcherbich (Russia)
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    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.