A declining trend observed in the abundance of fjord fish of the species Notothenia rossii marmorata and Notothenia gibberifrons from two localities of South Shetland Islands, is analyzed by a nested ANOVA and demonstrated as significant. The material studied was obtained with trammel nets at Potter Cove, King George/25 de Mayo I., from 1983 to 1990 and in waters around Half-Moon I., Moon Bay, in 1989. The analysis was based on the proportion of catches of the mentioned species in relation to Notothenia neglecta, a species with similar ecological habits in the fjords. Comparison with analogous published data obtained at close localities in the 60’s and 70’s, also shows a marked declination. This phenomenon in the area might be explained as a consequence of the depletion of the stocks due to commercial exploitation.