Fin whale (Balaenoptera physalus)
The fin whale is the second longest of all of the baleen whales, and has the typical rorqual body form, which is long, slender and streamlined. Fin whales produce a tall columnar blow that can be six metres high. The fin whale is found in all of the world’s major oceans. It is a migratory species that spends the winter months in temperate mid-latitude waters where it gives birth and mates and then it migrates to higher latitudes for intensive summer feeding.
The fin whale has the typical rorqual body form, which is long and slender (streamlined). It is the second longest of all of the baleen whales. Females reach lengths of about 24 metres in the Northern Hemisphere. Males are slightly shorter (22 m). Like most rorquals fin whales are dark grey on the back and light on the underside; both the belly and the underside of the flippers are almost white. The rostrum is narrow, with a single distinct ridge down the centre. The dorsal fin is 3/4 of the way back along the length of the body, and it is sickle-shaped. The colour of the fin whale’s head is very asymmetric; the left side is dark grey while the lower parts of the right side are white. Additionally, fin whales have ”chevrons”, which are light strips of brownish-grey that start just behind the blowhole and run back on the body in the shape of broad “V”s. Fin whales produce a tall columnar blow that can be six metres high. They only rarely show the flukes when they dive; the underside is white.
The fin whale is found in all of the world’s major oceans. It is a migratory species that spends the winter months in temperate mid-latitude waters where it gives birth and mates and then it migrates to higher latitudes for intensive summer feeding. But, some fin whales tend to remain in the north even in the winter, and there are no definitive wintering grounds known. It is thought that they may spend the winter months offshore. However, some of the fin whales that spend the summer in the North Atlantic winter as far south as the Gulf of Mexico in the west and the coast of Spain in the east. Additionally, some fin whales reside in the Mediterranean, where the species is found on a year-round basis.
The global population size is thought to be approximately 75,000 animals. In the northeast Atlantic there are thought to be 25,000-30,000 fin whales. The greatest numbers in this region are found off eastGreenland. Fin whales are loosely social, and are usually found in small flexible groups, although they can be seen singly and sometimes form large groups in areas with very high productivity. The groups do not appear to have any social bonding or cohesiveness. The sounds made by fin whales are quite simple, mostly consisting of groans and grunts or pulsed high-frequency sounds. There appears to be age and sex segregation within populations and there is different timing of migration between the different age and sex classes. Pregnant females migrate first, followed by adult males and non-pregnant females without young. Juveniles and lactating mothers are the last to migrate. Fin whales are fast swimmers, cruising at up to 15 km per hour and they are capable of burst swimming for short periods at speeds up to 28 kilometers per hour. Their dives are usually relatively short for such a large animal, lasting only 3-15 minutes, although they are capable of diving for 20 minutes. Depths are normally limited to the top 100-200 m. Fin whales feed on schooling planktonic crustaceans and a wide variety of small, schooling fish. They seem to prefer krill to anything else when it is available. They are also known to eat small squid. Killer whales are the only known natural predator of fin whales.
Life history and reproduction
Fin whales are born on the wintering grounds and accompany their mothers to higher latitudes during their first migration. They remain with their mothers for about 6-7 months. Gestation lasts about 11 months, so fin whale females usually give birth every second year. Northern hemisphere fin whales mate from December through to February. Little is known about their mating behaviour. Fins whales reach sexual maturity sometime between the ages of six and eight. They are thought to live to 80-100 years of age.
Management status and monitoring
Fin whales were not harvested in the early history of commercial whaling, because their rapid swimming speeds meant that they could out-run whaling ships. But, when steam-powered vessels and explosive harpoons were developed late in the 1800s fin whales became prime targets because of their large size. Currently, small numbers of fin whales are harvested in aboriginal fisheries off west Greenland and there is a small commercial take in Iceland. The Northeast Atlantic population is recovering from past overharvesting. The species remains protected in Norwegian waters including Svalbard, and there is an increasing number of observations in the region during the summer months along the west and north coasts of Spitsbergen and in the Hinlopen Stait.
MOSJ indicators (Environmental Monitoring of Svalbard and Jan Mayen):
Awaiting results from MOSJ…