Fin Whale

The **fin whale** (*Balaenoptera physalus*), also called the **finback whale**, **razorback**, or **common rorqual**, is a marine mammal belonging to the suborder of baleen whales. It is the second-largest animal after the blue whale, the largest growing to 27.3 m (89.6 ft) long and weighing nearly 74 tonnes (73 long tons; 82 short tons). American naturalist Roy Chapman Andrews called the fin whale "the greyhound of the sea... for its beautiful, slender body is built like a racing yacht and the animal can surpass the speed of the fastest ocean steamship."

The fin whale's body is long and slender, coloured brownish-grey with a paler underside.The fin whale is a large baleen whale that belongs to the cetacean order, which is composed of all species of whale, dolphin and porpoise. 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 ice pack 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 consists of small schoolingfish, squid, and crustaceans including copepods and krill.

Like all other large whales, the fin whale was heavily hunted during the 20th century and is an endangered species. Over 725,000 fin whales were reportedly taken from the Southern Hemisphere between 1905 and 1976, as of 1997 survived by only 38,000. The International Whaling Commission (IWC) issued a moratorium on commercial hunting of this whale, although Iceland and Japan have resumed hunting. The species is also hunted by Greenlanders under the IWC's Aboriginal Subsistence Whaling provisions. Global population estimates range from less than 100,000 to roughly 119,000.

### **Size**

In the Northern Hemisphere, the average size of adult males and females is about 18.5 m (61 ft) and 20 m (66 ft), respectively, while in the Southern Hemisphere, it is 20.5 m (67 ft) and 22 m (72 ft). In the North Atlantic, the longest reported were a 24.4 m (80.1 ft) male caught off Shetland in 1905 and a 25 m (82.0 ft) female caught off Scotland sometime between 1908 and 1914, while the longest reliably measured were three 20.7 m (67.9 ft) males caught off Iceland in 1973–74 and a 22.5 m (73.8 ft) female also caught off Iceland in 1975. Mediterranean population are generally smaller, reaching just above 20 m (65.6 ft) at maximum, or may possibly up to 21 m (68.9 ft) - 23 m (75.5 ft).

In the North Pacific, the longest reported were three 22.9 m (75.1 ft) males, two caught off California between 1919 and 1926 and the other caught off Alaska in 1925, and a 24.7 m (81.0 ft) female also caught off California, while the longest reliably measured were a 21 m (68.9 ft) male caught off British Columbia in 1959 and a 22.9 m (75.1 ft) female caught off central California between 1959 and 1970.

In the Southern Hemisphere, the longest reported for each sex were 25 m (82.0 ft) and 27.3 m (89.6 ft), while the longest measured by Mackintosh and Wheeler (1929) were 22.65 m (74.3 ft) and 24.53 m (80.5 ft). Major F. A. Spencer, while whaling inspector of the factory ship *Southern Princess* (1936–38), confirmed the length of a 25.9 m (85.0 ft) female caught in the Antarctic south of the southern Indian Ocean; scientist David Edward Gaskin also measured a 25.9 m (85.0 ft) female while whaling inspector of the British factory ship *Southern Venturer* in the Southern Ocean in the 1961–62 season. Terence Wise, who worked as a winch operator aboard the British factory ship *Balaena*, claimed that "the biggest fin [he] ever saw" was a 25.6 m (84.0 ft) specimen caught near Bouvet Island in January 1958. The largest fin whale ever weighed (piecemeal) was a 22.7 m (74.5 ft) pregnant female caught by Japanese whalers in the Antarctic in 1948 which weighed 69.5 tonnes (68.4 long tons; 76.6 short tons), minus 6% for loss of fluids during the flensing process. An individual over 27 m (88.6 ft) is estimated to weigh in excess of 120 tonnes (120 long tons; 130 short tons). A newborn fin whale measures about 6.0–6.5 m (20–21 ft) in length and weighs about 1,800 kilograms (4,000 lb).

### **Colouration and Markings**

The fin whale is brownish to dark or light gray dorsally and white ventrally. The left side of the head is dark gray, while the right side exhibits a complex pattern of contrasting light and dark markings. On the right lower jaw is a white or light gray "right mandible patch", which sometimes extends out as a light "blaze" laterally and dorsally unto the upper jaw and back to just behind the blowholes. Two narrow dark stripes originate from the eye and ear, the former widening into a large dark area on the shoulder — these are separated by a light area called the "interstripe wash". These markings are more prominent on individuals in the North Atlantic than in the North Pacific, where they can appear indistinct. The left side exhibits similar but much fainter markings. Dark, oval-shaped areas of pigment called "flipper shadows" extend below and posterior to the pectoral fins. This type of asymmetry is seen in Omura's whaleand occasionally in minke whales. It was thought to have evolved because the whale swims on its right side when surface lunging and it sometimes circles to the right while at the surface above a prey patch. However, the whales just as often circle to the left. No accepted hypothesis explains the asymmetry. It has paired blowholes on a prominent splashguard and a broad, flat, V-shaped rostrum. A single median ridge stops well short of the rostrum tip. A light V-shaped marking, the chevron, begins behind the blowholes and extends back and then forward again. The whale has a series of 56–100 pleats or grooves along the bottom of the body that run from the tip of the chin to the navel that allow the throat area to expand greatly during feeding. It has a curved, prominent dorsal fin that ranges in height from 26–75 cm (10–30 in) (usually 45–60 cm (18–24 in)) and averages about 51 cm (20 in), lying about three-quarters of the way along the back. Its flippers are small and tapered and its tail is wide, pointed at the tip, and notched in the centre. When the whale surfaces, the dorsal fin is visible soon after the spout. The spout is vertical and narrow and can reach heights of 6 m (20 ft) or more.

### **Vocalizations**

Like other whales, males make long, loud, low-frequency sounds. The vocalizations of blue and fin whales are the lowest-frequency sounds made by any animal. Most sounds are frequency-modulated (FM) down-swept infrasonicpulses from 16 to 40 hertz frequency (the range of sounds that most humans can hear falls between 20 hertz and 20 kilohertz). Each sound lasts one to two seconds, and various sound combinations occur in patterned sequences lasting 7 to 15 minutes each. The whale then repeats the sequences in bouts lasting up to many days. The vocal sequences have source levels of up to 184–186 decibels relative to 1 micropascal at a reference distance of one metre and can be detected hundreds of miles from their source.

When fin whale sounds were first recorded by US biologists, they did not realize that these unusually loud, long, pure and regular sounds were being made by whales. They first investigated the possibilities that the sounds were due to equipment malfunction, geophysical phenomena, or even part of a Soviet Union scheme for detecting enemy submarines. Eventually, biologists demonstrated that the sounds were the vocalizations of fin whales. Direct association of these vocalizations with the reproductive season for the species and that only males make the sounds point to these vocalizations as possible reproductive displays. Over the past 100 years, the dramatic increase in ocean noise from shipping and naval activity may have slowed the recovery of the fin whale population, by impeding communications between males and receptive females.

### **Breathing**

When feeding, they blow 5–7 times in quick succession, but while traveling or resting will blow once every minute or two. On their terminal (last) dive they arch their back high out of the water, but rarely raise their flukes out of the water. It then dives to depths of up to 470 metres (1,540 ft) when feeding or a few hundred feet when resting or traveling. The average feeding dive off California and Baja lasts 6 minutes, with a maximum of 17 minutes; when traveling or resting they usually dive for only a few minutes at a time.