Minke whales (p. [63]) have a falcate dorsal fin located in approximately the same position as that of the northern bottlenosed whale. However, minke whales have a flathead in front of their two blow holes and are black to dark gray on the back.
Sperm whales (p. [57]) have a squarish head that may somewhat resemble that of an adult male northern bottlenosed whale. However, there are numerous characteristics which will permit these species to be distinguished even from a distance:
| NorthernBottlenosed Whale | Sperm Whale |
|---|---|
| BLOW | |
| Low and bushy; projectsupward from indentation ontop of head. | Low and bushy, projectsobliquely forward from leftside of head; usually lessthan 8 feet (2.4 m). |
| COLORATION | |
| Lighter brown; adults splotchedwith grayish white;body smooth. | Brownish gray; body appearswrinkled. |
| FLUKES | |
| Rarely notched; seldom raisedon long dive. | Notched; raised on long dive. |
| HEAD | |
| Tapering in younger animals;bulbous in adults;white in older animals; beaked. | Squarish, long, all black;bbeakless. |
A further aid to distinguishing northern bottlenosed and sperm whales at sea is the fact that the sperm whales that are found in areas where northern bottlenosed whales are encountered are usually older, larger males from 40 to 60 feet (12.2 to 18.3 m) long. Northern bottlenosed whales do not exceed 32 feet (9.8 m).
Northern bottlenosed whales may also be confused with the poorly known North Sea beaked whale (p. [82]). When they can be examined at close range, however, northern bottlenosed whales should be distinguishable on the basis of the distinctly bulbous forehead.
Distribution
In the western North Atlantic, northern bottlenosed whales are restricted to Arctic and north temperate waters, where they most commonly occur in offshore areas. They have been reported from Davis Straits and the entrance to Hudson Strait, the Gully southeast of Sable Island, and as far south as Narragansett Bay, R.I.
In the spring and summer they concentrate near the northern limits of their range, occasionally visiting deep channels of the Gulf of St. Lawrence and eastern Newfoundland in summer. During these seasons they may extend to the edge of the pack ice.
In the fall and winter the bulk of the population migrates southward. Many probably winter in the Labrador Sea while others move farther southward and farther offshore.