Inter-individual and seasonal variability of biological indices in notothenioid fishes from Admiralty Bay, Antarctica – Pol. Polar Res

The ratio of N. coriiceps to N. rossii individuals in catches regularly increased during 22 years from 0.4 in 1977 to 9.5 in 1999. Oving to its reproductive strategy and avoidance of shallow waters N. rossii may be more vulnerable to overfishing. The condition factor was the most stable (CV 6–10%), variations in the of hepatosomatic index and index of stomach fullness were intermediate (21–38 % and 40–43%, respectively), and the gonadosomatic in− dex was the most variable (65–100%). Lack of seasonality in two somatic indices (condi− tion factor and index of stomach fullness) in N. coriiceps adults is a direct effect of high food availability and unlimited food detection all year round. In contrast, the seasonality of a reproductive index (gonadosomatic index) of these fish is a response to the highly sea− sonal trophic conditions for pelagic larvae. Key words: Antarctica, notothenioid fishes, endangered species, seasonal changes