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movements seem well established, whale marking suggests that 

 east-west movements of baleen whales between the six statistical 

 whaling areas are limited (Brown, 1962c) . Hence, when areas I 

 and V were set aside after World War II as whaling sanctuaries, 

 agreement was possible because these areas of low whale 

 abundance were unlikely to harbor stocks from outside the 

 sanctuaries. 



Gambell (1975c) noted that Antarctic populations of sei 

 whales appear to follow the general large baleen whale pattern 

 of breeding in equatorial or subtropical waters and then moving 

 south in the summer to feed. As noted previously, they do not 

 move as far south as other species such as fin, blue, and minke 

 whales (Gambell, 1968) . However, since sei whale harvest was not 

 economically attractive until the last decade, there is less 

 information on their movements than on those of other whales. 

 Whale mark recoveries to date are not adequate to clarify 

 important movements and statistically identify fine differences 

 in sei whale stocks (Brown, 1968b, 1968c) . 



c. Stock Identification 



An ecosystem perspective requires consideration of factors 

 beyond just numbers of individuals to allow proper management 

 of the system. Separate stocks within species must be identified 

 and managed in relation to the ecosystem as a whole. This 

 approach is supported by both domestic legislation (Marine Mammal 

 Protection Act of 1972) and international law (Convention for 

 the Conservation of Antarctic Seals) . 



1) Humpback Whale 



Humpback whales are generally thought to have six separate 

 stocks or populations in the Antarctic (Mackintosh, 1965; 

 Winn, 1976) and are perhaps the best example in this ecosystem 

 of a species with relatively well-identified stocks. Each 

 breeding stock migrates south during the summer to feed at which 

 time there is some stock intermingling. Chapman (19 74b) notes 

 that intermingling does not necessarily mean that the whales are 

 together physically, rather that different stocks have the 

 potential to enter the same statistical area in one season. 

 Some humpback whale stocks were depressed much farther than 

 others (Chittleborough, 1965; Mackintosh, 1970) . Therefore, 

 recovery of different humpback populations may progress at 

 different rates and may be variably sensitive to further eco- 

 system manipulation (differential exploitation of stocks within 

 other species, such as blue whales has also occurred) . Considera- 

 tion must be given to the ecosystem roles of individual humpback 

 populations as well as other Antarctic species in formulating a 

 conservation regime which allows further resource exploitation. 



