Subject: Abstract - migrating humpback whales (fwd)

Michael Williamson (
Tue, 6 Aug 1996 15:48:57 -0400 (EDT)


---------- Forwarded message ----------
Date: Tue, 6 Aug 1996 07:49:57 EST
To: Multiple recipients of list MARMAM <MARMAM@UVVM.BITNET>
Subject: abstract - migrating humpback whales

     Findlay, K.P. and P.B. Best.  1996.  Estimates of the numbers of
     humpback whales observed migrating past Cape Vidal, South Africa,
     1988-1991.  Marine Mammal Science 12(3): 354-370.

     (Mammal Research Institute, c/o S A Museum, P.O. Box 61, Cape Town,
     8000, South Africa)

     A 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 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.