Coastal distribution, movements and site fidelity of right whales Eubalaena australis off South Africa, 1969-1998

Counts and photographs of right whales Eubalaena australis taken on aerial surveys of the southern coast of South Africa between 1969 and 1998 have be en used to examine patterns of coastal distribution between successive 20-m inute bins of longitude. Some bins had consistently higher densities of wha les than others, either of cows with carves or of unaccompanied adults. Apa rt from an overall increase in density, the centre of distribution shifted 40-60 minutes of longitude to the west over the 30-year period. Most (< 93. 4%) female calves born on the South African coast returned there to have th eir first calf, but only 52.9% were photographed with their first calf in t he same or an adjacent bin as that of their natal year. This compares with 60.9% of multigravid females that occurred in the same or an adjacent bin a s that of their; previous calf, with significantly more westward (368) than eastward (255) shifts in distribution between calves. Approximate residenc e times for cow-calf pairs in the De Hoop region were 12-105 (average = 59. 0 +/- 3.9) days: dispersal rates were low between July and September but in creased thereafter. Incidental records of coastwise movement were mainly to the west, but were probably influenced by the survey direction. Distances moved ranged from 6 to 202 km. at average speeds of 0.08-2.89 km.h(-1). The odolite tracking of undisturbed groups of right whales from Cape Columbine produced a similar range of swimming speeds. Inter-calf movements of cows b etween the survey area and the coasts to both east and west indicated that the entire South African coast could be considered as one homogeneous winte r assemblage area for right whales.