Shannon Gowans, Hal Whitehead, Jakobina K. Arch and Sascha K. Hooker. 2000.
Journal of Cetacean Research and Management 2: 201-210.
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A population of northern bottlenose whales (Hyperoodon ampullatus) uses the Gully, a submarine canyon
off the coast of Nova Scotia, Canada. Eleven years of photo-identification records has permitted estimation of
population size using mark-recapture techniques. The population estimate was small (133 individuals, 95% CI = 111-166
from left side identifications; 127 individuals, 95% CI = 106-160 from right side identifications). The population
was not closed, with the combined mortality, mark change and emigration rate estimated at 13% per year for left
side identifications (95% CI = 9-17) and 14% for right side identifications (95% CI = 10-18). There was no significant
increase or decrease in the population size between 1988-1999 (change in population size: left side: -0.13% per year,
95% CI = -3.4 to 3.9; right side -0.43% per year, 95% CI = -4.5 to 3.1). The sex ratio was roughly 1:1, with equal
numbers of sub-adult and mature males. Over the summer field season, individuals emigrated from, and re-emmigrated into
the Gully, spending an average of 20 days within the Gully before leaving (left side identifications 19 days, SE = 17;
right side identifications 23 days, SE = 10). Approximately 34% of the population was present in the Gully at any time.
Individuals of all age and sex classes displayed similar residency patterns although there were annual differences as
individuals spent less time in the Gully in 1996 than in 1990 and 1997. Sighting rates were similar in all years with
extensive fieldwork, indicating little variability in the number of whales in the Gully each summer. Accurate estimates
of population size and residency patterns will be useful in determining the regulations and required coverage for
a marine protected area in the Gully.
Keywords: Mark-recapture; Photo-id; Trends; Population Assessment; Northern bottlenose whale