MOVEMENTS BETWEEN THE ANTARCTIC AREAS 373 



MOVEMENTS BETWEEN THE ANTARCTIC AREAS 



It has been explained that the division of the Antarctic whaling grounds into Areas I-VI is not 

 purely arbitrary; there are grounds for believing that at least some of them represent a real grouping 

 of the whale populations, more distinct in Humpbacks than in other species. The divisions between 

 the areas, however, may eventually need adjustment and some may have more reality than others. 

 In any case it is worth while to compare the movements of whales between these areas, so far as they 

 have been demonstrated by whale-marking. 



In a discussion of the grouping of Blue and Fin whales, Mackintosh (1942) drew attention to the 

 recoveries of whale-marks described by Rayner (1940), and noted that since more whales moved 

 between Areas III and IV, than between Areas II and III, there might be a more real distinction 

 between the two latter. No whale has yet been shown by whale-marking to cross from one area to 

 another within the course of a single whaling season and Mackintosh points out that it seems likely, 

 therefore, that movement from one area into another takes place either in temperate regions or in the 

 course of the migration. Again, no whale has yet been demonstrated to move from one area, across 

 a second area, and into a third, a distance of at least 6o° of longitude (70 if across Area III), but two 

 Blue whales, No. 2026 dispersing 63 10' eastward and No. 5456 moving 86° 58' westward travelled 

 a sufficient distance to have done so had they been marked near the boundary of an area. The time- 

 charts for Fin and Blue whales (Figs. 2, 3, 4 and 12) show the movements between Areas I-IV which 

 have been recorded to date. No marked whales have yet been recovered in Area V but whaling was 

 not carried on regularly during every season in this area before 1946-47. 



Movements of Fin whales. Twenty-five of the 201 marked Fin whales recovered are known to have 

 moved from one area into another (Table 4). In order to compare the amounts of movement between 

 the different areas it is necessary not only to allow for the number of whales marked in each Area 

 but also to allow for the chance of a marked whale being captured in each Area. For this again a 

 coefficient must be used, which represents the chances of a marked whale being caught in that Area. 

 Here it is convenient to use the ratio of recoveries within the Area rather than the total number 

 caught, and the correction is made as follows. The number of whales marked in the Area (given in 

 Table 5) is divided by the number of these marks recovered in that Area to give a coefficient which 

 will be high when the chances of recovery are low, and vice versa. Then the number of marked whales 

 crossing into the Area has been multiplied by this coefficient to give a corrected number representing 

 the total marked whales calculated to have crossed into the Area, including those not captured. The 

 corrected number has then been expressed as a percentage of the whales marked in the Area from 

 which they have moved. 



The calculation is shown in Table 4. Taking the second line as an example, a total of 2233 whales 

 have been marked in Area II, and six of these were recovered in Area III. In Area III 1186 whales 

 had been marked of which forty-two were recovered in the same area, i.e. 1 in 28-24 which is the 

 coefficient. From this it is calculated that 169 or 7-6% of all the whales marked in Area II moved 

 into Area III during the whole period in question, whether or not they were recaptured. 



Assuming that the marked whales were a fair sample of the population the implication is that 

 7-6% of the whole population of Area II moved into Area III in the same period; but of course it 

 must be remembered that the small numbers of marked whales involved does not permit these 

 figures to be used to draw more than a broad comparison between the various movements. The 

 100% arrived at in the first line of Table 4 is no doubt quite unrealistic, but it seems evident that 

 much more movement takes place in the eastward direction between Areas I and II than between 

 any of the other areas. The corresponding westward movement, from Area II to Area I, cannot be 



3-2 



