Fin whale

The fin whale, the second largest living mammal, has been severely impacted worldwide by commercial whaling. Nearly 750,000 animals were killed in areas of the Southern Hemisphere alone between 1904 and 1979, and they are rarely seen there today. Their current status is unknown in most areas outside of the North Atlantic.

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Fin whale, Sea of Cortez, Mexico
© WWF / Nature PL / Mark Carwardine

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  • Common Name

    Fin whale, common rorqual, fin-backed whale, finback, finner, herring whale, razorback; Baleine fin, baleine à nageoires, baleinoptère commune, rorqual commun (Fr); Ballena aleta, ballena boba, rorcual comùn (Sp)

  • Scientific Name

    Balaenoptera physalus

  • Status

    IUCN: Endangered

  • Population

    Approximately 30,000 individuals

  • Length

    19 - 20 m

  • Weight

    About 70,000 kg

  • Skin

    Dark grey to brownish black, with pale or white undersides

Physical Description

The fin whale is the second-largest living animal, after the blue whale. This animal 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 60 cm 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 slimmer and not as heavy as blue whales. On average, 85 ventral grooves run along the underside of their body and there are 350-400 baleen plates in their mouths.

Fin whales are found in all the oceans of the world, but their migration patterns are not well understood. In the Southern Hemisphere, fin whales migrate south to feed on krill and other plankton in the summer, and north to likely give birth in warm waters closer to the Equator in the winter. However, it is not clear whether all of the population engages in this migration every year.

In the Northern Hemisphere there are similar north-south migrations, and many whales appear to return to the same feeding grounds every year, but the pattern is not so clear, perhaps because of the influence of the Gulf Stream in the North Atlantic. Populations of northern and southern hemispheres never meet.

Size

Adult fin whales are about 19 m long for males and 20 m for females, with a maximum of 25 m in males and 27 m in females. It is estimated that a 25-metre whale would weigh about 70,000 kg.

Colour

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.

This species has a rare characteristic among mammals, known as asymmetrical pigmentation: the lower right jaw is bright white, the lower left jaw black. The reason for this unusual coloring is unknown, but some scientists have speculated that fin whales circle schools of fish with the white side facing the prey and frightening them into denser schools that are easier for the whale to catch.
 / ©: WWF-Canon / Y.-J. REY-MILLET
Fin whale Balaenoptera physalus Mexico. Balaenoptera physalus Fin whale Baja California Mexico
© WWF-Canon / Y.-J. REY-MILLET

Ecology & Habitat

Almost no feeding for more than one season
Fin whales are pelagic and coastal species, sometimes occurring in shallow waters (30 m).

Social Structure

Although the species is mostly observed as single animals, fin whales are also sometimes seen in pairs, or in groups (or pods) that commonly count 6 to 7 individuals. However, up to 50, and occasionally as many as 300, travel together on migrations. Social structure seems to vary by area, and may be related to differences in age or feeding strategies.

Life Cycle

Young fin whales nurse for 6-7 months. Having reached approximately 12 m in size, they follow the female to the high latitude feeding areas. Sexual maturity is reached between 6 to 11 years. The life span of a fin whale is around 85 to 90 years.

Breeding

It has been assumed that mating occurs when the whales are in warm waters, but no breeding grounds have been observed. Females give birth every 2-3 years and the gestation period is 11 to 11.5 months. Usually a single offspring is born, reaching 650 cm long and weighing almost 2 tons.

Diet

During autumn and winter, there is almost no feeding, at which time whales are found in lower latitudes. 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, and euphausiids (krill - shrimp-like crustaceans) and copepods which are small crustaceans.

The fin whale, like other baleen whales, strains its food from the water through baleen plates.
 / ©: Kevin Schafer WWF Canon
Fishing boat coast of Unalaska Island near Dutch Harbour, Alaska, USA
© Kevin Schafer WWF Canon

Population & Distribution

Not fast enough for whalers
Previous population and distribution

Prior to the invention of the steam engine, whalers were unable to match the amazing speed of the fin whale, and they were largely saved from commercial whaling. That all changed in the early 20th Century, and the global fin whale population was quickly reduced by commercial whaling. Almost 750,000 fin whales were reportedly killed in the Southern Hemisphere between 1904 and 1979 - almost half of these in a single decade in the 1950s.

Current population and distribution

The fin whale has a global distribution, occurring in the north Pacific, north Atlantic, Indian and Arctic Oceans, as well as in the Mediterranean. In the North Pacific, fin whales are found in the Bering and Chukchi Seas, and along the coast of Alaska while in the North Atlantic, they can be seen around Canada, Greenland, Iceland, northern Norway, Spitsbergen and the Barents Sea. They are relatively rare in tropical or iced polar seas. In areas of the southern hemisphere where the species was once hunted intensively, they are rarely encountered today.

The total population in the North Atlantic probably exceeds 46,000.
Fin whale range / ©: Wikipedia
Fin whale range
© Wikipedia
Range States
Angola, Argentina, Australia, Bangladesh, Brazil, Canada, Ecuador, Faroe Islands, French Polynesia, French Southern Territories, Greenland, Hong Kong, Iceland, India, Indonesia, Italy, Japan, Kenya, Democratic People's Republic of Korea, Republic of Korea, Madagascar, Mexico, Myanmar, Namibia, New Zealand, Norway, Pakistan, Poland, Portugal, Russian Federation, South Africa, South Georgia and the South Sandwich Islands, Spain, Sri Lanka, Suriname, Svalbard and Jan Mayen, Taiwan (China), United Republic of Tanzania, Tunisia, United Arab Emirates, United Kingdom

Ecological Region
Antarctic Peninsula and Weddell Sea, Bering-Beaufort-Chukchi Seas, Barents-Kara Seas, Mediterranean Sea, Northeast Atlantic Shelf Marine, Grand Banks, Chesapeake Bay, Yellow Sea, Okhotsk Sea, Patagonian Southwest Atlantic, Southern Australian Marine, New Zealand Marine, California Current, Benguela Current, Humboldt Current, Agulhas Current, Western Australia Marine, Panama Bight, Gulf of California, Galapagos Marine, Canary Current, Nansei Shoto, Sulu-Sulawesi Seas, Bismarck-Solomon Seas, Banda-Flores Sea, New Caledonia Barrier Reef, Great Barrier Reef, Lord Howe-Norfolk Islands Marine, Palau Marine, Andaman Sea, Tahitian Marine, Hawaiian Marine, Rapa Nui, Fiji Barrier Reef, Maldives, Chagos, Lakshadweep Atolls, Red Sea, Arabian Sea, East African Marine, West Madagascar Marine, Mesoamerican Caribbean Reef, Greater Antillean Marine, Southern Caribbean Sea, Northeast Brazil Shelf Marine.

What are the threats to the fin whale?

With krill reduced, will they go too?
Fin whales have been greatly affected by historical hunting, mostly due to their economically valuable blubber, oil and baleen. The recovery of the southern hemisphere fin whale may be undermined by, among other things, a reduction of Southern Ocean krill due to climate change.

Pollution

Fin whales are also threatened by habitat degradation. In some regions 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.

Ship strikes

Boat collisions are another serious cause of fin whale mortality, particularly in areas with high-speed vessel traffic. A dead fin whale that was washed ashore in south-west England in early 2010 is believed to have been the victim of a ship strike.

Bycatch

They are also vulnerable to incidental catches in fishing gear, but less so than many other cetacean species.

Whaling

Whaling remains a threat for this species. In 2006 Iceland resumed commercial whaling and in 2009 set a quota for 150 fin whales over 5 years – to date 125 fin whales have been harvested – despite the species' status as "Endangered".
A fin whale is butchered by Icelandic whalers. / ©: Jonas Fr. Thorsteinsson
A fin whale is butchered by Icelandic whalers in December 2006 after the Icelandic government allowed the resumption of commercial whaling.
© Jonas Fr. Thorsteinsson

What is WWF doing?

WWF efforts in this area over the coming years will be directed towards increasing awareness of the need for cetacean conservation at the national and regional levels, and to create opportunities for local communities to be involved in, and to profit from, cetacean conservation initiatives.

The majority of WWF's global conservation work to protect whales and dolphins takes place within the context of the International Whaling Commission (IWC).
Together we can make the world's oceans safe for whales. / ©: WWF / Ogilvy Indonesia
Together we can make the world's oceans safe for whales. Learn more about WWF's work to protect whales.
© WWF / Ogilvy Indonesia

How you can help

  • Support efforts to improve fishing gear by only buying seafood that is MSC certified. This can help to reduce the incidence of marine bycatch, which kills whales and other marine life like turtles, dolphins, and seabirds.
     
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Did you know?

    • The fin whale can sustain a speed of around 37 km/hr, and can leap completely out of the water.

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