Age and growth of ocellated icefish, Chionodraco rastrospinosus DeWitt and Hureau, 1979, from the South Shetland Islands |
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Authors: | Mario La Mesa Julian Ashford |
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Institution: | (1) ISMAR-CNR, Istituto di Scienze Marine, Sezione di Ancona, Largo Fiera della Pesca, 60125 Ancona, Italy;(2) Center of Quantitative Fisheries Ecology, Old Dominion University, 800 West 46th Street, Norfolk, VA 23508, USA |
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Abstract: | Age and growth of ocellated icefish, Chionodraco rastrospinosus, were investigated using counts of annual growth increments from sagittal otoliths. Samples were collected during research
surveys by benthic trawl carried out around Elephant and South Shetland Islands in January–February 2002 and December 2006–January
2007. A total of 290 specimens were selected for the study, consisting of 120 females and 170 males. The age of fish was estimated
by counting annuli on transverse sections obtained by grinding and polishing whole otoliths embedded in epoxy resin. The precision-of-age
estimates within and between readers were tested applying both the average percent error (APE) and the coefficient of variation
(CV). The estimated age-range was 1–12 for both sexes of C. rastrospinosus. Applying the von Bertalanffy growth function to the age–length data, a growth curve was obtained for each sex. The estimated
values of VB growth parameters L
∞
and k were, respectively, 47.9 cm and 0.28 for females and 42.9 cm and 0.36 for males. Compared to other congeneric species, the
growth performance of C. rastrospinosus was relatively high, being 2.82 and 2.81 in males and females, respectively. Age at sexual maturity was estimated to be about
4 years in both sexes. C. rastrospinosus captured in the studied area consisted mainly of adult specimens between 3 and 8 years, with few older fish. |
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Keywords: | Age and growth Ocellated icefish South Shetland Islands Antarctica |
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