Age and growth of spiny icefish (Chaenodraco Wilsoni Regan, 1914) off joinville-D'Urville Islands (Antarctic Peninsula)

Age and growth of spiny icefish (Chaenodraco wilsoni) were investigated using counts of annual growth increments from sagittal otoliths. Samples were collected during research surveys by benthic trawl carried out off joinville-D'Urville Islands (Antarctic Peninsula) in February-March 2006 and January 2007. A total of 218 specimens were selected for the study, consisting of 120 females and 98 males. The age of fish was estimated by counting annuli on transverse sections obtained by grinding and polishing whole otoliths embedded in epoxy resin in moulds. The precision of age estimates between readings was tested applying both the average percent error (APE) and the coefficient of variation (CV). Conversely, the accuracy of age estimates was not tested, so that present ageing data have to be considered with caution. The estimated age range was 1-5 years for males and 1-4 years for females of C. wilsoni. Applying the von Bertalanffy (VB) growth function to the age-length data, a growth curve was obtained for each sex. The estimated values of VB growth parameters L-infinity (cm) and k were respectively 32.7 and 0.81 for females and 32.7 and 0.68 for males. Age-at-sexual maturity was estimated to be about 2 years for females and 2.5 years for males. Like other icefishes, C. wilsoni exhibited a high growth rate until it reached sexual maturity although it had a much shorter life span. The part of the population Of C. wilsoni caught in the study area consisted mainly of adult individuals between 1 and 3 years of age, with very few older fish.