Whales

Bowhead Whale - Balaena mysti cetus

Bowhead Whales are the only baleen whales to spend their entire lives in the Arctic waters, unlike other whales that migrate for feeding or reproduction. Some have been found off Alaska, and having spent the winter months in the Bering Sea, they migrate northward in the spring, hunting food such as plankton and krill.

They are dark in colour, with a maximum weight of 136 tonnes and growing up to 20 meters in length. These whales have no dorsal fin and a strongly bowed lower jaw and narrow upper jaw. Their baleen plates, are the longest of the baleen whales, and are used to strain their prey from the water. They have massive bony skulls with which they use to break the ice from beneath to breathe. Their head makes up 40 % of their body length. The blubber of these whales is thicker than any other animal, with an average of 50 centimeters.

Breeding has been observed to be from March through to August, with conception occurring mainly in March. Females bear a calf once every 3 to 4 years, with pregnancy lasting 13 to 14 months at a time. A newborn weighs approximately 1 tonne, growing to 9 meters by its first birthday. Sexual activity occurs between a boisterous group of several males and one or two females.

Bowhead Whales are very vocal and use underwater sounds to communicate. Their long repetitive songs may possibly be mating displays. Even though they may spend at least forty minutes underwater at a single time, the Bowhead whale is not thought to be a deep diver. As very slow swimmers, they usually travel alone or in small herds of up to six animals.

These whales perform spyhopping, which has been defined as when a whale comes out the water vertically, and momentarily stays out of the water, in a manner similar to when a human treads water. This type of behaviour may well be used so that the whale can examine its surroundings above the surface. They also do much lobtailing, by slapping their tail hard against the water. It seems that lobtailing is more common within species that are social, than those of solitary animals. The sound of a lobtail can be heard underwater for several hundred meters. This has led to speculation amongst scientists that lobtailing is, like breaching, a form of non-vocal communication. However, studies of Bowhead whales have shown that the noise of a lobtail travels much less than that of a vocal call or a breach. Thus the lobtail is probably important visually as well as acoustically, and may be a sign of aggression.

The lifespan of a Bowhead was once thought to be similar to other whales, which is approximately 60 to 70 years. However, recent discoveries of antique ivory spear points found in these whales in the 1990’s, suggests that some individuals have lived to be 150–200 years old. One report even suggests that a female at the age of 90 years, was allegedly still reproductive.