Samples of fish collected from 1983 to 1992 at Potter Cove, King George Island, South Shetland Islands, are used to study the decline in abundance previously reported fro fjord Notothenia rossii, in association with changes in the size and age structure of the juvenile population. Mean lengths increased in correlation with poor recruitment to inshore waters and sharply decreased as stronger year classes entered the cove. In comparison, Notothenia neglecta, a non commercially fished species with similar ecological habits in the fjords, showed little variations around the expected overall mean size, without any significant trend. Thus, the changes in the juvenile N. rossii population are not thought to be caused by local factors, but related with the operations of the commercial fishery during the late seventies in the area, mainly around Elephant Island. Data from 1991 and 1992 might be indicating the beginning of a recovery of the N. rossii population in Potter cove.