Photo by B. Evans
Whale species > The Bowhead Whale
Photo by B. Evans
Compared to the other great whales, bowheads are relatively compact, rotund black whales up to 19.8m long, with heads that are about a third of their body length. They have a highly arched, narrow upper jaw and a large, lower jaw, two blowholes, and no dorsal ridge or fin. With these large heads and powerful bodies, bowhead whales are capable of breaking through sea ice at least 20cms thick: Inuit hunters in Alaska have reported whales surfacing through 60cms of ice.
Bowhead whales are only found in the Northern Hemisphere, in the arctic waters of northern Europe, Canada, Greenland, the Hudson Bay area, the Okhotsk Sea, and the Bering, Chukchi, and Beaufort seas between Alaska and Russia. They migrate within these waters rather than moving seasonally to more temperate waters like other great whales. The fact that they stay in the Arctic year-round, moving between summer feeding and wintering areas, make bowheads one of only three whale species that spend their entire lives in the Arctic.
Bowhead whales have the longest baleen of all the mysticete whales, with a maximum length of four metres. Bowheads filter their food through baleen, opening their mouths and straining zooplankton from the surface, the water column, or the sea floor. Zooplankton includes copepods and small shrimp-like animals called euphausiids. Scientists estimate that a bowhead whale needs to eat about 100 tonnes of crustaceans each year. They maintain a thick layer of blubber that insulates them from the icy arctic waters. Bowhead whales often congregate in the autumn in areas with rich food resources. One such area is Isabella Bay near Clyde River, Nunavut, Canada, which WWF is helping to preserve as a whale sanctuary.
Bowhead calves are born between April and June. Because these whales do not have teeth - often used to estimate age in other mammals - it can be difficult to determine their age. However, other data shows that bowhead whales may be among the longest-lived animals on earth. Based on the recovery of stone harpoon tips in their blubber, and from analysis of eye tissue, scientists believe bowhead whales survive to until they are well over 100-years-old. One individual in a study was believed to be more than 200 years old. Killer whales prey on bowheads, and some bowheads die when they become trapped or frozen in heavy ice.
Hunted by commercial whalers until the last century for oil, meat, and baleen, bowhead whales are today listed as endangered species in many countries. Some populations are faring better as a result. Some native Alaskans and Canadian Inuit are allowed a limited subsistence hunt for bowhead whales from stable populations.
Modern threats include habit loss and toxics, which accumulates in the Arctic and which may negatively affect the health and reproduction of bowhead whales.