G-^fi 



Reported catches in Area 4I show a rapid build up to a peak of over 400 000 t followed 'by 

 a rapid decline to a few thounand tons the following years,. The decline in total catch can 

 be attributed to two causes, fewer vessels and/or a lower catch rate. The very great reduc- 

 tion in catch rate from 10 to 2 ton/hr indicates a great reduction in stock density. This 

 factor in itself suggests that the total catch in the first few years was something approach- 

 ing the initial standing stock level. Ignoring natural additions to the population, and 

 assuming that the change in catch rate accurately reflects an 8O/J drop in population, then 

 the catch would have been 80^ of the initial stock. This suggests an initial standing 

 stock of about 500 000 t for the South Geor,"ia Shelf area. 



In area 51 (assumed to refer to Kerguelpn) the more gradual decline in reporxed catch 

 suggests that the hij^iest figure vjas appreciably less than the initial standing stock whilst 

 at the same time since the catches have declined from year to year they are probably still 

 (1974) hif^er than the MGY. These catch fi.^jireB therefore indicate an initial standing 

 stock of well in excess of 220 000 and an fCY of loss than 80 000 ton/yr. 



Information on fish biomass production is available from two additional sources, 

 EVerson (l970a) in a detailed analysis of Notothenia noglecta in a small area (part of Borge 

 Day, 3ign,y Island) estimated that the mean biomans was 194 kg/hectare and that annual pro- 

 duction was 66 kg/hectare. Tlie annual production in this study was estimated over the whole 

 demersal phase of the lifespan. 



Production by sexually mature fish vra.s only about one third of this. Although this 

 figiare is very probably an overestimate of production by the fishable stock there is no 

 iniormation to indicate v;here a more realistic demarcation should be made. A second estimate 

 of fish production in the Southern Ocean is given by the estimated annual consumption by 

 predators. Estimates for fish consumption by whales, seals and birds have been made by Laws 

 (1977) and Croxall (unpublished MS) .These are siunraariscd in Table 8.32. 



Table 8.32. Consumption of Antarctic fish by V/hales, Seals and Birds 

 (Data from Lavra 1977, and Croxall unpublished I'lS) 



J/ 



Since preparing these estimates my attention has been drawn to a study of the fish stockB 

 In the Kerguelen area, Ilureau (in press) using results from a trawling survey estimated 

 the standing stock of demersal fish to be about 120 000 t and their MST to be about 

 20 000 t (or about 0.4 t/km^ of shelf area). The disparity between his results and those 

 presented above, is a further indication of the incomplete nattire of most of the infor- 

 mation necessary for these assessments and underlines the importance of reported catch 

 statistics for fish stock assessments. 



