The Fin whale are the second largest of all whales species after the Blue whales. Famed for their ability to sustain high speeds they have been called the “greyhound of the sea”.
Common Name: Fin Whale
Other Names: Finback Whale
Scientific Name: Balaenoptera physalus
Conservation Status: Vulnerable/Endangered
Length: New-born calves 5+ metres, Adult Females 18 to 27 metres, Adult Males 17 to 25 metres.
Weight: Birth weight is about 2 tonnes. Adults weigh up to 70 tonnes.
Field Identification
– Huge!
– Tall, narrow shaped blow from two blow holes.
– Dark grey in colour graduating to pale grey to white along their abdomen white markings.
– Their heads are asymmetrical in colour, being dark grey in colour with the right lower jaw being white.
– Baleen plates are black on the left jaw and white on the right jaw.
– Dorsal fin up to 60cm in size is set two-thirds of the way along the back, and is curved and often slopes backwards.
– Longitudinal ridges on the head.
– Rarely shows its tail flukes.
– Indifferent to boats.
Taxonomy
For a long time there were two recognised subspecies of fin whale. B. physalus quoyi, which occurs in the Southern Hemisphere, and B. physalus physalus, which occurs in the Northern Hemisphere.
In 2004 a third subspecies which has been called the Pygmy Fin Whale (B. physalus patachonica) was described by Clarke (2004) based on a specimen that stranded in Argentina. Little is know about this third subspecies.
Description
The Fin Whale is the second-largest whale species, after the Blue Whale. They are dark grey to brownish black along their top sides which graduates to pale grey to white along their abdomen. Their undersides as well as undersides of the flippers and flukes are white. Their heads are asymmetrical in colour, being dark grey in colour with the right lower jaw being white. Baleen plates are black on the left jaw and white on the right jaw. They do not have the mottling that Blue Whales do.
Adult whales range between 20 and 27 m long and weigh more than 70 tonnes. The females are larger in size than the males. Fin Whales are very streamlined in appearance, with a distinct ridge along the back behind the dorsal fin. The dorsal fin which can be up to 60cm in size is set two-thirds of the way along the back, and is curved and often slopes backwards.
Distribution and Movement Patterns
Australia – In Australian waters Fin Whales have been seen off the southern states during summer and into autumn (November to May). They have also been seen off the Australia’s Antarctic Territory and their calls detected Antarctic waters from February to July. They have been seen in areas with complex sea floors where their prey species are known to concentrate.
It is believed that Fin Whales migrate between Australian waters and their Southern Ocean feeding grounds (Antarctic and Subantarctic) and their tropical breeding grounds (Indonesia, the northern Indian Ocean and south-west South Pacific Ocean).
Globally – Fin whales are considered a cosmopolitan species that can be seen in the deep ocean from the tropics to the polos in the deep ocean. They very rarely visit coastal waters. They have well defined migratory patterns between the polar regions and the tropics. They appear not to like being too close to the ice unlike Blue and Minke Whales.
Fin whales are known to congregate in the South Pacific Ocean, the Southern Ocean and the Indian Ocean including off the coasts of New Zealand, Peru, Brazil and South Africa.
During migration, fin whales are segregated by sex as well as age with the males migrating first, followed by the pregnant females with the immature whales migrating last.
Population
Reliable estimates of fin whale population are not know due to the difficulties in studying them. It appears that natural fluctuations in food availability affects the numbers seen in any particular area from year to year. Acoustic recordings in Antarctic waters have suggested that there may be two different populations within the Southern Ocean. Their numbers were severely affected by commercial whaling.
Habitat
The Southern Ocean between Australia and Antarctica are know as important feeding grounds for Fin Whales. They have also been seen feeding in the Bonney Upwelling which is a rich seasonal upwelling that occurs in the eastern Great Australian Bight, extending from Ceduna, South Australia in thew west, to Portland, Victoria in the east between November to May.
There are no known breeding to calving grounds for Fin Whales in Australian waters although a Fin Whale mother and calf have been seen in the Bonney Upwelling, suggesting this area may be an important area for them, perhaps as a provisioning area for mothers with calves.
Behaviours
Fin whales are known to be more gregarious than other species of baleen whales. Whilst single or pairs are more common they are know to gather in pods of ten or more whales and even pods of over 100 whales have been seen in their feeding grounds.
Fin Whales calls are a pulsed almost mechanical rumble sound of very long duration of around 30 seconds. These calls have been heard during the breeding season so may be related to the males mating displays.
Feeding
In their Southern Ocean feeding grounds Fin Whales consume large amounts of Krill, fish and other crustaceans using lung or skimming feeding methods at or near the surface. They are also known to feed at depth.
Life Cycle
Fin whales become sexually mature between the ages of six to ten years and when they have reached a length of around 19 (males) to 20 (females) meters. The breeding season is from May to July with gestation lasting around 11 months. It is believed they breed every two to three years. This slow breeding rate has significant implications population recovery. Calves are around six to seven metres at birth and are weaned about six to seven months later. Life expectancy is up to nearly 100 years. Natural mortality rates are unknown but Killer Whales and some shark species are known predators.
Threats
Like all marine mammals Fin Whales have a number of natural and man made threats.
Natural – predation by Killer Whales and sharks. Disease and old age.
Man Made – Pollution, climate change, acoustic disturbance, ship strikes, entanglement and bycatch, over-harvesting of food sources such as Krill.
References/Sources
Australian Department of the Environment, Canberra
Whales, Dolphins and Porpoises by Mark Carwardine
Whales, Dolphins & Seals: A Field Guide to the Marine Mammals of the World by Hadoram Shirihai and Brett Jarrett
Copyright 2020 David Jenkins – Whale Spotter