Fin whale (Balaenoptera physalus)
Description: Fin whales are the second largest whale species after the Blue whale. Females reach 24 metres body length and up to 75 tons weight; males reach a size of 22 metres. The body is long and slim, with a dark-grey upper side and a pale underside. The sickle-shaped dorsal fin is far back at three quarters of the body length. The asymmetric colouration of the head is an important diagnostic feature: The left side is dark-grey, the lower part of the right side is white. Also the baleen is dark on the left and pale on the right side. Fin whales have a strong blow, up to six metres high. Distinguishing them from other whales can be tricky.
Distribution / migration: Fin whales occur in all of the world’s oceans. They spend the winter in temperate waters where mating and birthing take place, but prefer the rich feeding grounds of high latitudes during the summer. The north Atlantic population winters in the open sea, possibly in the latitudes between Spain and the Gulf of Mexico or even in the Mediterranean. During the summer, they can be seen in Spitsbergen, especially off the west coast in the area where the continental shelf drops down to the deep sea basin, but they can be seen anywhere, including coastal waters and fjords. They are most common closer to East Greenland.
Biology: Fin whales tend to stay in smaller groups, but both single animals and larger herds occur, if food availability is good. Cows and bulls go separate ways. They are fast swimmers and can reach up to eight knots (14 kilometres per hour) while travelling and up to 14 knots (27 km/h) during sprints. Fin whales rarely dive longer than 15 minutes or deeper than 200 metres on their search for plankton, which is their exclusive diet.
Miscellaneous: This large whale species has been hunted extensively since the invention of the explosive harpoon in the late 19th century. The global population may be around 75,000 animals, of which about 25,000-30,000 are in the North Atlantic. They are globally protected, with the exception of limited hunting in West Greenland, and numbers are increasing, although there is some loss as bycatch in fishing nets. Overfishing of food resources and environmental toxins are current dangers. The latest threat for these and other whales is the LFAS system (Low Frequency Active Sonar) of the US Navy, which creates incredible sound pressures of up to 215 decibels, meaning that the noise at a distance of as much as 480 kilometres is still 140 decibels, equivalent to a rifle shot.
The life expectancy of these majestic animals is close to a century. Hybrids between Fin and Blue whales have been seen.
last modification: 2014-10-27 ·
copyright: Rolf Stange