Monitoring of relative abundance of fjord Notothenia rossii, Gobionotothen gibberifrons and Notothenia coriiceps at Potter Cove, South Shetland Islands, in years 2000 to 2003

The monitoring program of demersal fish at inshore sites of the South Shetland Islands has continued in Potter Cove from 2000 to 2003, covering a continuous sampling period of twenty years and in Harmony Cove, Nelson Island, in the austral summers from 2001 to 2003. The decline in trammel net catches of fjord fishes of the species Notothenia rossii and Gobionotothen gibberifrons in relation to the non commercially fished Notothenia coriiceps, which was already reported for the period 1983-1999, is still evident. At Potter Cove, higher catches of N. rossii were obtained from 1991 to 2000, but the actual levels of relative abundance of this species and of G. gibberifrons are well below those found in the early 1980s. At Harmony Cove, the relative abundance of N. rossii showed an increase in years 2002-2003, whereas G. gibberifrons was absent in the catches. No recovery of the stocks of these two fish species was still observed, more than two decades after the end of the commercial fishery. However, the increase observed in the catches of N. rossii in some years since 1997 might be indicative of events of higher recruitment, not yet confirmed by the offshore scientific surveys carried out in the region. The results are consistent with diet information of the piscivorous Antarctic shag Phalacrocorax bransfieldensis in the South Shetland-Antarctic Peninsula area obtained from the early 1990s.