Fin whale

The fin whale (Balaenoptera physalus), also known as the finback whale or common rorqual is a species of baleen whale. It is the second-longest cetacean on Earth after the blue whale. The largest reportedly grow to 26 m (85 ft), with a maximum recorded weight of 77,000–81,000 kg (170,000–179,000 lb). The fin whale's body is long and slender, coloured brownish-gray with a paler underside.

At least two recognized subspecies exist, in the North Atlantic and the Southern Hemisphere. It is found in all the major oceans, from polar to tropical waters. It is absent only from waters close to the pack ice at the poles and relatively small areas of water away from the open ocean. The highest population density occurs in temperate and cool waters. Its food mainly consists of small schooling fish, squid, and crustaceans including copepods and krill. Mating takes place in temperate, low-latitude seas during the winter. Fin whales are often in groups of 6–10 animals, and they communicate with frequency-modulated sounds ranging from 16 to 40 hertz.

Like all other large whales, the fin whale was heavily hunted during the 20th century. Over 725,000 fin whales were reportedly taken from the Southern Hemisphere between 1905 and 1976. Recovery of the overall population size of southern subspecies is predicted to be at less than 50% of its pre-whaling state by 2100 due to heavier impacts of whaling and slower recovery rates. As of 2018, it was assessed as vulnerable by the International Union for the Conservation of Nature.

Recent genetic studies indicate that fin whales routinely mate with blue whales, and they produce viable offspring capable of reproducing. Studies suggest that this has been due to the slow recovery rate of both species in response to whaling in the early 20th century, creating a population bottleneck encouraging interspecies mating between the two species.