WHALE MARKING 273 



The evidence of the northward migration to the north-west Australian coast from the 

 Queen Mary Land ground shown by the ^-Group is repeated by the ii-Group 

 (Plate LXV), this time with ten recoveries situated between Dick Hartog's Island and 

 North- West Cape. But another similar northward migration is disclosed by a recovery 

 (No. 9326) off the south coast of Madagascar. This whale was marked well to the south 

 of 6o° S and about io° E, and thus, in addition to the considerable movement north- 

 wards, there is also a fairly wide latitudinal movement. 



It is curious that no Humpbacks have yet been taken after two years, but recoveries 

 in the 2|-Group, four in all, have been made off the north-west Australian coast 

 (Plate LXVI). The one recovery (No. 5509) in the 3-Group on the Queen Mary Land 

 ground shows the persistent return to this region (Plate LXVII). 



Although containing only one record (No. 2779) the 31-Group is of special interest, 

 for this recovery was also made on the whaling grounds off the southern point of 

 Madagascar (Plate LXVI 1 1). This whale had been marked quite close to Enderby Land 

 and a considerable distance east of the other Madagascar recovery (No. 9326). It is 

 possible that the Humpback whales found in the small region to the south of Madagascar 

 are drawn from a much larger area of the Antarctic than those migrating to the north-west 

 coast of Australia. It is noteworthy that no marked Humpback whale has been taken at 

 Durban, where the catch is, however, smaller than on the Madagascar ground. It seems 

 probable that the route followed by Humpbacks to and from the Antarctic may give 

 Durban a wide berth and the whaling there may not tap the main stream of migration. 

 There is no instance yet of latitudinal dispersal of Humpbacks from one region of abund- 

 ance to another; in comparison with Blue and Fin whales the Humpback shows less 

 initiative and seems content to follow the same routes, returning to the same region 

 season after season. This is in agreement with the opinion hitherto held of its very regular 

 migration and has enabled this species to be so heavily exploited in the past that some 

 of the migratory streams have practically ceased, for example, that formerly passing 

 South Georgia. The large provinces into which the Humpback stock might fall appear 

 to be much more rigid and self-contained than those of the other species. 



PERCENTAGE RETURN OF MARKS 



The opinion has already been expressed that more marked whales are killed than are 

 reported, for it is not to be expected that marks will invariably be found. Further, the 

 numbers of whales given as effectively marked (Table I) are considered to be maximum 

 figures, for some marks may be lost from these whales before capture. There may also 

 be a wastage of marked whales through natural death or accidents. In the circum- 

 stances it is difficult to know exactly what value to place on the figures of percentage 

 returns given in Table V, but these figures may be looked upon as reasonably reliable 

 when considered relatively to each other, for the disturbing causes mentioned above 

 must be acting more or less equally on the three species. 



