Preliminary results of an age/length study of juvenile Notothenia rossii marmorata from Potter Cove, South Shetland Islands

Whole otoliths and scales were used for a simultaneous age determination of juvenile Notothenia rossii marmorata specimens collected at Potter Cove, King George/25 de Mayo Island, South Shetland Islands. Results from the analysis of both structures agreed in 95.5%. Likewise, the examination of otolith cross sections of chosen specimens confirmed in all the cases the age readings obtained from the second whole sagittal otolith. First October instead of the commonly accepted 1 July, was taken as the birth date of the fish, which is discussed. The length-age range of the fish was 18-44 cm and 3-7 years respectively, which is well in accord with the known length-age distribution of juvenile specimens of the species in the fjord. Mean length data at age presented here were compared with published values for specimens of the same area. Our data are similar to the ones reported previously for fish of Admiralty Bay, King George/25 de Mayo I. The use of whole otoliths for age determination of juvenile N. rossii marmorata proved to be a reliable method. However, it might be not viable for adult specimens.