The State of Exploited Fish Stocks in the Atlantic Sector of the Southern Ocean

Summary

Finfish have been harvested around South Georgia since the end of the 1960s mainly by the Soviet Union. Notothenia rossii marmorata was the target species in the first peak years 1969–71, which yielded about 500 000 tonnes in two seasons. Since 1975/76 fishing has been directed mostly to the icefish Champsocephalus gunnari and to a lesser extent Patagonotothen brevicauda guntheri. Catches of C. gunnari were highest at about 240 000, 220 000 and 100 000 tonnes in 1976/77–1977/78, 1982/83–1983/84 and 1986/87–1987/88.

N. rossii marmorata is the species most adversely affected by the fishery. The present stock size is less than 5% of the level before the fishery started. Recruitment has fallen since the second half of the 1970s. At the present level of recruitment, simulation studies indicate that the stock will recover slowly, only doubling over a period of 10 years.

Stock size of C. gunnari around South Georgia is largely dependent on the strength of the recruiting year class which also forms the bulk of catches in the fishery. Stocks of C. gunnari around the South Orkney Islands and in the Antarctic Peninsula region seem to be heavily depleted by fishing and are in need of conservation measures.

Patagonotothen br. guntheri is the only species for which the fishery was unregulated until 1988/89. Stock assessment is largely influenced by uncertainties in the determination of the natural mortality rate (M). At high levels of M (0.8–0.9) stock size as well as recruitment indicate a downward trend.