Fin Whale

Balaenoptera physalus

The fin whale is the second-largest species of whale. It can grow to 26 metres long and weigh up to 80 tonnes. It has a sleek body with a V-shaped head. It has a distinctive tall, hooked dorsal fin about two-thirds of the way along its body. There is a distinct ridge running between the dorsal fin and tail - some people call them razorbacks. Fin whales are black or brownish grey on their back and sides and white on the underside. They have grey or white chevron markings on their head. Their lower jaw is distinctively coloured - it is dark on the left and light on the right side.

Authority

Linnaeus, 1758

Classification Details

Phylum: Chordata (chordates); Subphylum: Vertebrata (vertebrates); Class: Mammalia (mammals); Infraorder: Cetacea (whales and dolphins); Superfamily: Mysticeti (baleen whales).

Habitat

Fin whales are found in all major oceans. There are three subspecies of fin whales that occur in different areas. Fin whales are often in groups of two to seven individuals. In the summer, fin whales feed in northern or southern cold waters. During the summer months in eastern Canada, they are present in the Gulf of St Lawrence, on the Scotian Shelf, in the Bay of Fundy, and off Newfoundland and Labrador. They migrate in winter to breeding and calving areas in tropical waters, but not all whales go every year.

Diet

Filter feeders. They swim through patches of prey, taking large volumes of water into their mouth. They then filter the water out through their baleen plates, trapping prey on the hair-like fringes of the plate. They have between 260 and 480 baleen plates. They brush the prey from the baleen plates using their tongue and swallow it. Their food includes krill, small fish (herring, capelin, sand lance), and squid. A fin whale can eat up to two tonnes of food every day.

Reproduction

Sexes are separate. We don't know much about mating in this species. Males become sexually mature between 6 and 10 years of age and females from 7 to 12 years. Females give birth to a single calf after a gestation period of 11 to 12 months. Females travel to the tropics to give birth. Calves are around six metres long when they are born, and their mothers feed them on milk for six months. Fin whales can live for over 100 years.

Fun Facts

This species is endangered throughout its range. Commercial whaling killed vast numbers of whales from the mid-1900s to the 1980s. Pre-commercial whaling populations in the North Atlantic were around 30 000 to 50 000 individuals. There are now about 3000. Today fin whales are mainly killed by entanglement in fishing gear and by vessel strikes. But a few countries, such as Iceland, do continue to hunt this endangered species.

Scientists have found that fin whales sometimes mate with blue whales, creating hybrids. Some of these hybrids are fertile (an uncommon trait in hybrid animals).

Fin whales are known as the greyhounds of the sea — they can swim at speeds of over 45 kilometres per hour for short bursts.

References

COSEWIC (2005) COSEWIC assessment and update status report on the fin whale Balaenoptera physalus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. ix + 37 pp. (www.sararegistry.gc.ca/status/status_e.cfm).

Eder T (2012) Whales and Other Marine Mammals of Atlantic Canada. Vancouver: Lone Pine Publishing.

NOAA (2021) Fin Whale. Species Directory. https://www.fisheries.noaa.gov/species/fin-whale#overview
Accessed online 11 May 2021.

Pampoulie C, Gíslason D, Ólafsdóttir G, Chosson V, Halldórsson SD, Mariani S, Elvarsson B, Rasmussen MH, Iversen MR, Daníelsdóttir AK and Víkingsson GA (2020) Evidence of unidirectional hybridization and second generation adult hybrid between the two largest animals on Earth, the fin and blue whales. Evolutionary Applications 00, 1– 8. https://doi.org/10.1111/eva.13091.

Perrin WF (2020). World Cetacea Database. Balaenoptera physalus (Linnaeus, 1758). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=159023 Accessed online 20 January 2020.