Linnaeus, 1758 - Bowhead whale
Distinctive Characteristics
Bowhead whales are extremely rotund overall, but often have a distinct “neck” region. The head is large (up to one-third of the body length); the upper jaw is arched and narrow when viewed from above. The mouthline is strongly bowed, and the eye is placed just above the corner of the mouth. There is no dorsal fin or ridge, and the back is very broad. The flippers have blunt tips and the flukes are wide with smooth contours. There is a large muscular bulge (the stack) in the blowhole area.
Predominantly black in colour, bowheads have a white patch at the front of the lower jaw; this patch often has several dark grey to black spots, each indicating the position of a chin hair. There is also often a light grey to white band around the tail stock, just in front of the flukes, and sometimes other white or light grey areas on the body. The white on the tail expands with age, and very large, old bowheads may have an almost completely white tail. Some lighter coloured bowheads are occasionally seen.
Bowheads have the longest baleen plates of any whale. The 250 to 350 plates in each side of the jaw can reach lengths of 5.2 m; they have long, fine fringes. The plates are dark grey to brownish black, generally with slightly lighter fringes. As is true for the closely related right whale, the blow is V-shaped and bushy.
Can be confused with
Gray whales use some of the same summer range as bowheads, but the gray whale's dorsal hump and knuckles, and differences in head and body shape, coloration, and behaviour between the 2 species should make them distinguishable. Right whales might also overlap with bowheads, but usually the 2 species are separated by their ecological preferences. The right whale's callosities and absence of light chin and peduncle patches will allow them to be distinguished from bowheads.
Size
Male bowhead whales>bowhead whales range to 18 m in length, females to 20 m. Weights of large individuals have been estimated at about 75 to 100 t. Calves are about 4 to 4.5 m long at birth.
Geographical Distribution
Bowheads are found only in arctic and subarctic regions. There are several stocks in the North Atlantic Ocean, and the Bering, Beaufort, Chukchi, and Okhotsk seas. These animals live much of their lives among the pack ice, migrating to the high arctic in summer, but retreating southward in winter with the advancing ice edge.
Biology and Behaviour
Bowhead whales are usually seen in groups of 3 or fewer, but larger aggregations form during the autumn migration and on the feeding grounds. Although often slow-moving, bowheads breach and engage in other aerial behaviour. They frequently lift their flukes before a steep dive. Low frequency calls are common, at least during migration.
Calves are born mainly in spring as whales migrate toward feeding grounds. The breeding system is thought to be similar to that of the right whale, with males using a form of sperm competition. Small to medium-sized invertebrates, especially krill and copepods, form the bulk of the bowhead's diet. Bowheads skim feed at the surface and feed in the water column. It has recently been suggested that they also feed near the bottom, but probably do not directly ingest sediments as gray whales routinely do. During surface skim feeding, coordinated group patterns have been observed, including whales feeding in echelon (V-shaped) formation.
Exploitation
Bowhead whales were heavily hunted for several centuries. Today they are partially protected by the IWC. The current world population is still threatened by small-scale hunting by Alaskan, Canadian, and Russian natives. In addition, there are various forms of habitat degradation, including disturbance from oil and gas exploration and development activities.
IUCN Status
Vulnerable.