Abstract
AbstractA recovery‐monitoring program of the African east coast humpback whale population was carried out through shore‐based visual surveys from Cape Vidal, northern Natal. Surveys of the northward migration were undertaken each winter from 1988 to 1991, and a survey of the southward migration was undertaken in 1990. Independent observer surveys were undertaken during June 1990 and during the entire 1991 survey. Hourly densities of groups sighted each day were adjusted for groups missed by observers with distance from the shore and under different sighting conditions. Densities were multiplied by 24 h and the mean group size of the survey year to give resulting daily densities of individuals, which were summed to provide totals of whales sighted during each year's survey. The best estimate of population size was 1,711 (made during the northward migration of 1990), although this is likely to be biased downwards by a proportion of the population passing outside of observers’view. Bootstrapping of the 1991 daily data resulted in CVs between 11.4% and 12.2%. The numbers sighted show the population to have undergone considerable recovery since protection in October 1963.
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