G-37 



The total figure i.i able 8.32 is made up of all Antarctic fish species and not just 

 those of potential commeroial importance. Total production by those species of potential 

 commercial importance is therefore likely to be less than this figure although by how muoh 

 is not known. Tlie growth patterns of the fish species within the area, since most belong to 

 the same taxonomic group (Nototheniiforms) , may well follow the same sort of pattern. This 

 being the case, the production by sexually mature fish is probably about one third of the 

 total (i.e., about 5 million tons). 



The tendency for Antarctic fish to produce large yolky demersal eggs indicates a 



reliance on the Continental or Island Shelf areas for at least part of their life histories. 



South of the Antarctic Coiwergence the Continental and Island Shelves cover an area of 



fi ? 1 / 

 approximately 2.2 x 10 km —'. The total production estimated from consumption by predators 



averaged over the shelf area is 7-75 ton/km^. 



The fact that this figure is only slightly larger than the production figure for Noto- 

 thenia neglecta should not be taken as any indication of precision since both estimate s are 

 subject to considerable error because one applies to one species (the dominant one in the 

 study area) in a restricted shallow water area and the other relates to all species over the 

 whole Southern Ocean. The figures should be taken as only an indication that they are of 

 the right order of magnitude rather than being truly representative of the actual situation. 



If these figures of production are applied to the 36 000 km^ (approx. ) of the South 

 Georgia Shelf area, the estimated figures for that area are 230 000 - 280 000 ton production. 

 The production figure applies to the whole demersal lifespan and since only about )}, of this 

 is due to sexually mature fish the production that is of interest to a fishery would be 

 77 000 ton/yr, and since the stock of sexually mature fish is almost certainly greater than 

 the fishable stock these figures must be overestimates. 



These estimates have been summarized in Fig. 8.3« 



Erring on the side of caution and therefore taking the lowest figure, a MSY of 50 000 

 ton/yr is indicated for the South Georgia area. 



In the absence of any more sophisticated or precise estimates of production the same 

 estimates if applied to the Kerguelen shelf area (approx. 50 000 km2) indicate a total pro- 

 duction of 230 000 to 300 000 tons and a production of sexually mature fish of from 77 000 

 to 100 000 tons. Assuming that the lower figure is a reasonable. estimate of MSY this figure 

 is approximately what would be expected from intuitively inspecting the reported catch in 

 recent years (see Table 8.27). 



It is important to bear in mind that the production figures discussed above apply, with 

 the exception of those for Notothonia noglecta at Signy Island to all fish within the 

 Antarctic zone. Although the Sign,y Island study was undertaken on only one species, it is 

 fairly certain that within the area of the investigation Notothonia neglecta was by far the 

 dominant species in terms of biomass. The suggested MSY for South Georgia and Kerguelen are 

 therefore a total for all opecios in tho particular areas. Without knowledge of the propoi^ 

 tion of species present it is impossible to partition the MSY even between major groups. 



In the abBwice of any further information, it la reasonable to assume that a figure of 

 approximately 1«5 ton/lon2 (see footnote to p, 110) is Applloable to the other shelf areas. 



— ' This figure excludes the major ice shelf zones. 



