Fin whale

The fin whale (Balaenoptera physalus) is second only in size to the blue whale. Males of 22m and females of 24m have been recorded in the northern hemisphere, while fins in the southern hemisphere are even larger.

Fin whales are dark grey to brownish black, with pale or white undersides.
The undersides of the flippers and flukes are also white. Some fin whales have a pale grey chevron on each side behind the head and there may be a dark stripe running up and back from the eye, and a light stripe arching down to where the flipper joins the body.

The fin whale is very streamlined in appearance with a distinct ridge along the back behind the dorsal fin, which gives it the nickname "razorback". The dorsal fin, which is about 60cm high, is set two thirds of the way along the back. The jaw is large and when the mouth is closed the lower jaw protrudes slightly beyond the tip of the snout.

Fin whales are fast and may swim up to 41km per hour when alarmed, 30km per hour in short bursts when migrating or cruising, and two to 6.5km per hour when feeding. During migration, they swim about 145km a day. They dive to more than 200m, deeper than either the blue or sei whale.

Where are they found?
Like other baleen whales, fin whales migrate to cooler northern waters in the spring for summer feeding, and to temperate waters in the autumn for breeding and calving. Summer is the best time to see fin whales in the Arctic. In the North Atlantic, fin whales can be seen around Canada, Greenland, Iceland, northern Norway, Spitsbergen and the Barents Sea. The total population in the North Atlantic probably exceeds 46,000. In the North Pacific, fin whales are found in the Bering and Chukchi Seas, and along the coast of Alaska.

What do they eat?
Fin whales, like other baleen whales, strain their food from the water through baleen plates. Fin whales feed on krill, some fish and cephalopods. The diet varies between areas and seasons. Herring, capelin and other shoaling fish are eaten in both the North Atlantic and North Pacific, along with squid, euphausiids and copepods.

How long do they live?
In the Northern Hemisphere, lengths at sexual maturity are about 18m in females and 17m in males. Breeding takes place in the winter and the gestation period is 11.25 months. Calves are nursed for six to seven months. Fin whales are often solitary animals, but can form pods of up to 20 animals. The life span of a fin whale is around 85 to 90 years. Killer whales occasionally attack fin whales.

Fin whales and hunting
As with other large whales that have been hunted commercially, fin whale numbers have fallen. Small numbers are still hunted in Greenland for aboriginal subsistence needs.

Conservation concerns
Fin whales are threatened by environmental change and habitat loss. They have been shown to carry high levels of pollutants such as heavy metals, PCBs and other organochlorine compounds that accumulate with age and transfer between mother and calf during nursing. These substances can cause health and reproductive problems in cetaceans.