Alternative population estimates of humpback whales (Megaptera
novaeangliae) in Hawaiian waters
- Baker, C. S. and Herman, L. M.
Based on a census of photographically identified
humpback whales in Hawaiian waters during the years 1977 –
1981. J. D. Darling and H. Morowitz (1986. Can. J. Zool. 64:105-111)
estimate that the number of individuals visiting this breeding ground
is 1000 during a single winter and 2100 across five winters. Confidence
limits are not reported for either estimate, however, and the authors
so not consider fully the potential biases of their capture –
recapture analyses. A test of the frequency of capture model used
for the within year analysis showed, in some cases, a poor fit between
the theoretical distribution and the reported data, thus indicating
that the resulting population estimates may also be incorrect. Alternative
estimates of across years abundance were calculated using data from
an independent study of humpback whales in Hawaiian waters conducted
during the years 1980 to 1983. From the resighting records of the
519 whales identified during this period, Petersen and Jolly-Seber
models provide estimates ranging from 635 to 1536 individuals for
contiguous sampling years. These estimates are difficult to reconcile
with the larger across years estimate of Darling and Morowitz and
suggest that further study is needed to accurately assess the status
of this endangered population.
Baker, C. S. and Herman, L. M. (1987). Alternative population estimates
of humpback whales (Megaptera novaengliae) in Hawaiian waters. Canadian Journal of Zoology, 65, 2818-2821.
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