Fin Whale Facts | Iceland Wildlife Guide

Physical Characteristics

The fin whale is the second largest whale in existence weighing between 45 and 75 tons. It measures between 62 and 76 feet in length (females are generally larger), with the longest recorded animal spanning 85 feet long. The body shape of the fin whale is streamlined and bears a set of wide, triangular tail flukes. Its dorsal fin sits about two-thirds back from its pointed head and curves backward. The fin whale ranges from brown-black to dark gray in color, with a white underside and between 55 and 100 throat grooves. The known lifespan of this species is about 60 years.

The fin whale is very similar to other rorquals, except for its massive size. Only the blue whale is larger than the fin whale. The easiest way to tell the two whales apart is by observing their dorsal fins; after a blow, the fin whale’s dorsal appears quickly, while the blue whale’s dorsal takes longer to show.

Habitat & Geographic Distribution

Fin whales are a pelagic and near-shore species, sometimes swimming in water as shallow as 100 feet deep. They are widely distributed but are less common in tropical waters than temperate waters. In the North Pacific, fin whales can be found in the Bering and Chukchi Seas, the coast of Alaska, around the Aleutian Islands and off the coast of the coast of Baja, California. Historical accounts from the 1960s indicate that the fin whale was formerly the most abundant large whale off California in spring and summer. In the North Atlantic, fin whales spend the summer in a broad region between North America and the Arctic, around Greenland, Iceland, Northern Norway, Spitsbergen and the Barents Sea. In the winter, they are distributed from the ice edges to the Caribbean, the Gulf of Mexico and the British Isles, to the Bay of Biscay and the Mediterranean.

Similar to other large baleen whales, fin whales migrate towards the poles in the spring and to warmer waters in the fall. Some pods congregate inshore during winters in the North Atlantic and North Pacific, while others reside in areas like the Gulf of California year-round.

Feeding Habits

The fin whales’ diet is dependent on its environment and the time of year. In the North Pacific and North Atlantic, fin whales feed on fish such as capelin and herring, as well as squid, copepods, and planktonic crustaceans. Krill and other amphipods are a staple of Southern Hemisphere fin whale diets.

A fin whale usually consumes prey by lying on its side on the ocean’s surface and gathering an enormous mouthful of water and food as its buccal cavity expands. The fin whale filters its catch through its baleen before swallowing; there are 520 to 950 baleen plates per animal, the largest of which is 36 inches in length. The amount of food consumed daily by fin whales has been calculated as one to 1.5 tons in the North Pacific, 2.8 tons in the Antarctic and 0.533 tons off the northeast coast of North America.

Behavior

There are three fin whale populations that do not interbreed, grouped in the North Atlantic, the North Pacific and the Southern Hemisphere. Within these separate populations, pods of fin whales travel back and forth between mating and feeding grounds. During migration, these whales may travel in groups of up to 300 animals. However, they are usually found in couples or in small groups of six to ten fin whales. Fin whales communicate with each other through groans, clicks, and pulses, and are able to dive up to 750 feet under water.

Breeding

By the age of ten, male fin whales have reached sexual maturity. Females reach sexual maturity a bit earlier, between three and twelve years of age, and will reproduce every two or three years thereafter. Full physical maturity is not attained, however, until 25 and 30 years of age.
  
Fin whales are thought to be monogamous, as they are often seen in pairs. Mating occurs during the winter in warm, low latitude seas and calving usually occurs twelve months later. As many as six fetuses have been reported, but single births are the norm. Newborns measure about 14 to 20 feet in length and weigh nearly two tons. Young whales nurse for six or seven months and are weaned after they reach about 30 to 40 feet. Weaned calves will then travel with their mothers to the winter feeding grounds.

Human Exploitation

After hunting dramatically decreased the population of the blue whale, the fin whale became the favored target of whalers, primarily due to its comparable size. Like the blue whale, once it became hunted, the fin whale population declined greatly.

The major whaling years occurred between 1935 and 1965. Each year an estimated 30,000 fin whales were slaughtered. Due to the extreme number of fin whales killed, the International Whaling Commission placed them under full protection in 1966. The population today is said to be around 50,000, which is only a fraction of its former numbers. Unfortunately, it is unlikely that the species will ever return to its pre-whaling population.

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