What is a fin whale? The fin whale (Balaenoptera physalis) is the second largest species of whale. It is a threatened species. It is thought that there were once around half a million fin whales in the oceans in the southern hemisphere. Now, there may only be about 25,000 fin whales left in the southern half of the world, as numbers were reduced drastically by historic whaling before the species was fully protected. 

What does it look like? This huge marine mammal grows to 27 metres long, and weighs up to 90 tonnes. It has a narrow, streamlined body and a fairly tall fin on its back. The upper parts of the whale’s body are dark grey or dark brown, but the tail and the flippers have white patches underneath. The head is dark but the white right lower jaw and the white baleen plates give it a striking appearance and help to distinguish it from any other type of whale. 

Fin Whale

Where does it live? The fin whale is found worldwide. It migrates between warm-water breeding grounds and cold-water feeding grounds, but migration routes do not follow coastlines. 

What does it eat and how? Fin whales feed mostly on Antarctic krill (tiny shrimp-like marine crustaceans) but may also consume schools of squid and fish. A filter feeder, it gulps up huge quantities of this prey then strains away the water by using hundreds of horny baleen plates that hang from its upper jaws. These have bristly edges which mesh to form a filter. They can spend months without feeding, as they can get their energy from fat stored in their blubber. 

Behaviour: The fin whale is a fast-swimming species that is usually seen only in deeper parts of the ocean. 

Breeding and caring for young: Fin whales reach adulthood and begin to breed at about six to ten years of age, when they are around 19 metres long. A single calf will be born in spring about one year after mating. 

Protecting the fin whale: There are no records of live fin whales stranding along the Western Australian coast. A dead fin whale was washed ashore at Perth’s Cottesloe Beach about 20 years ago. Report any observations of live or dead stranded or entangled whales to the Wildcare Helpline so that specially trained department staff can assess and help the animals as required.