-84- 



N. rossi marmorata, Champsocephalus gunnari , and 

 Pseudochaenichthys georgianus ) schools feed on krill 

 patches offshore in summer, and disperse from April to 

 December (Marchall, 1964; Andriashev, 1965; Keysner et al., 

 1974; Laws, 1977b) . Dissostichus mawsoni also migrates 

 north to the Convergence to feed on krill (Yukhov, 1970) . 



Considerable evidence suggests that species spawning 

 in subantarctic coastal waters or on the continental shelf 

 of Patagonia also make extensive summer fattening migrations 

 into Antarctic waters. Among these, the Patagonian hake and 

 southern blue whiting are already commercially exploited 

 north of the Convergence (Everson, 1977). Two other species, 

 Notothenia magellanica and Dissostichus elenginoides , also 

 enter Antarctic waters annually. (Permitin, 1969; Lyubimova 

 et al. , 1973) . 



3. Stock Identification 



Evidence for multiple management stocks is unavailable 

 for most Southern Ocean fish. Table 18 gives information 

 about subpopulations of two species . 



4 . Standing Stock 



Antarctic fish biomass and productivity data are quite 

 limited. Everson' s (1970a) intensive study of Notothenia 

 neglecta at Signey Island showed that mean biomass was 194 kg/ 

 hectare and that annual production was 66 kg/hectare. Esti- 

 mates of the biomass of the Patagonian hake stock, which 

 migrates into the Southern Ocean, is from 3 to 6 million 

 metric tons (Everson, 1977) . 



Present information suggests that much of the reported 

 catch adjacent to Antarctic waters consists of Antarctic 

 Nototheniiformes. Reported catches have led to estimates 

 of an initial standing stock of about 500,000 metric tons 

 for the South Georgia Shelf area (which may have been 

 reduced by as much as 80% by intensive fisheries) . Similar 

 data indicate an initial standing stock of 220,000 metric 

 tons with an estimated maximum sustainable yield (MSY) of 

 80,000 metric tons/year north of Kerguelen. However, 

 trawling serveys suggest initial standing stocks of 120,000 

 metric tons with a MSY of 20,000 metric tons/year. This 

 disparity underlines the need for further research and 

 reporting of complete catch information (Everson, 1977) . 



5 . Production 



There is little published on seasonal reproductive 

 cycles of Antarctic fish. Spawning periods vary between 



