-30- 



latitudinal and longitudinal segregation within species between 

 age classes and sexes (Laws, 1960a, 1961, 1977b; Mackintosh 

 1965; Dawbin, 1966) . Older individuals appear to occupy more 

 southerly areas in locations of dense zooplankton concentrations, 

 and pregnant or lactating females arrive at different times 

 depending on their particular reproductive status. Laws (1977a) 

 proposed that these segregation patterns may have been the 

 result of competition for food, implying that food availability 

 may have been limiting to the whale populations prior to major 

 whaling and commercial exploitation. 



Gulland (1974) , suggested that cetacean distribution is 

 related to the basic productivity of various oceanic areas. 

 Although whale abundance and primary productivity levels did not 

 necessarily correlate well, he showed very good correlations 

 between baleen whale and zooplankton densities (particularly 

 krill) , Baleen whales are more confined to areas of high zoo- 

 plankton biomass than are sperm whales which feed on secondary 

 consumers such as squid. Gulland also examined the relative 

 catch levels of whales in the different statistical areas 

 (Figure 9), and found that Sections II and III had much higher 

 total catch levels than other areas. Section IV had a moder- 

 ately high catch level. While these figures suggest that 

 Sections II, III, and IV were more productive than areas I, V, 

 or VI, Gulland cautioned that since most whaling was concentra- 

 ted in these areas, the catch figures may have a strong bias. 



b. Movements 



Every year, whales migrate from their northerly breeding 

 grounds to the cold Antarctic waters primarily to feed on krill 

 and other zooplankton (Mackintosh, 1970, 1972a) (Figure 10). 

 Whale concentrations feed in a narrow circumpolar band along the 

 pack ice edge as it moves south in the summer (Mackintosh, 1973) . 

 As the pack ice begins to move north in the fall, the whales 

 return north to their tropical and subtropical breeding grounds 

 (Mackintosh, 1972a) . Figure 11 outlines the movements of female 

 fin whales in relation to time of year, reproductive status, 

 and pack ice distribution as well as their annual intensive 3 

 to 5 month feeding periods. Figure 12 presents information on 

 principal movements between breeding and feeding grounds ob- 

 tained from marked sei, humpback, and fin whales. 



Movements of Southern Ocean baleen whales, particularly 

 those that migrate long distances, appear to have regular 

 features. Dawbin (1966) stated that migrations of blue, fin, 

 humpback, and sei whales are staggered. Blue whales are the 

 first to arrive in the feeding grounds, fin and humpback whales 

 coming second, and sei whales generally arriving last (Laws, 

 1977b) . Southern right whales do not appear very migratory and 

 rarely penetrate polar waters (Laws, 1977b). Whereas north-south 



