. The Canadian field-naturalist. Natural history. 288 The Canadian Field-Naturalist Vol. 111. Figure 1. Northern Bottlenose Whale photographed in the Gully showing signs of entangle- ment in fishing gear. at any time are about 57% of a population number- ing about 230 animals (Whitehead et al. 1997; H. Whitehead, unpublished). The geographic range of this population is unknown but, based on the pat- tern of sightings, we suspect that it is principally the slope waters south of Nova Scotia. If the Gully animals are an integral, freely-mixing part of the population off northern Labrador, then th
. The Canadian field-naturalist. Natural history. 288 The Canadian Field-Naturalist Vol. 111. Figure 1. Northern Bottlenose Whale photographed in the Gully showing signs of entangle- ment in fishing gear. at any time are about 57% of a population number- ing about 230 animals (Whitehead et al. 1997; H. Whitehead, unpublished). The geographic range of this population is unknown but, based on the pat- tern of sightings, we suspect that it is principally the slope waters south of Nova Scotia. If the Gully animals are an integral, freely-mixing part of the population off northern Labrador, then the total population numbers only about 230 animals — unlikely given the numbers and geographical spread of recent sightings in northern waters (Reeves, Mitchell and Whitehead 1993). The population analysis (Whitehead et al. 1997) does not rule out occasional migrations of animals between the northern (Labrador-Davis Strait) areas and the Gully. The estimates of mortality + emigra- tion + mark change are about 12% per year, and have wide confidence limits. We have no objective means of allocating the 12% between these three possible causes. No estimates of mortality are avail- able for Northern Bottlenose Whales, although mor- tality is believed to be about 6% per year in the Sperm Whale (Physeter macrocephalus), the species most ecologically similar to the Northern Bottlenose for which data are available (Rice 1989). Thus we can only conclude from the population analysis that emigration rates from the Gully population, and immigration rates into it, are probably less than about 10% per year and may be negligible. Additional evidence that the Northern Bottlenose Whales in the Gully are largely distinct from those off Labrador comes from an examination of length distributions (Whitehead et al. 1997). The photo- graphically measured animals in the Gully are about m shorter than those caught off northern Labrador. The same effect is true for the two sexes: the Labrador populat
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