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Fin Whale

(Balaenoptera physalus)

Short Description

The Fin Whale is the second largest whale in the world, and belongs to the rorquals, a family that includes the humpback whale, blue whale, Bryde's whale, sei whale, and minke whale.

By definition, rorquals all have a dorsal fin and throat grooves that expand when the animal is feeding. The Fin Whale, or Finback Whale is second only to the blue whale in size and weight. Among the fastest of the great whales, it is capable of bursts of speed of up to 35 km/hr (23 mph) leading to its description as the "greyhound of the sea."

Its most unusual characteristic is the asymmetrical colouring of the lower jaw, which is white or creamy yellow on the right side and mottled black on the left side. Fin whales are found in all oceans of the world, though they seem to prefer temperate and polar waters to tropical seas.

Long Description

Size
Adult males measure up to 25 m (75 feet) in the northern hemisphere, and 27 metres (88 feet) in the southern hemisphere. The reasons for this are unknown, but may be diet related. As with all rorquals, the females are slightly larger than males. Weight for both sexes is between 45,000 and 65,000 kg) (50-70 tons).

Identification
The fin whale is long, sleek, and streamlined, with a V-shaped head which is flat on top. A single ridge extends from the blowhole to the tip of the rostrum (upper jaw). They have between 50-100 pleats or grooves on the underside of its body extending from under the lower jaw to the navel. 

Light gray to brownish-black in colour on its back and sides, two lighter "coloured" chevrons begin midline behind the blowholes and slant down the sides towards the fluke (tail) before turning and ending right behind the eye.

The underside of its body, flippers, and fluke are white. The lower jaw is gray or black on the left side and creamy white on the right side. This asymmetrical coloration extends to the baleen plates as well, and is reversed on the tongue.
The fin whale has a prominent, slightly falcate (curved) dorsal fin located far back on its body. Its flippers are small and tapered, and its fluke is wide, pointed at the tips, and notched in the centre. 

Diet
Fin whales feed mainly on small shrimp-like creatures called krill or euphausiids and schooling fish.

They have been observed circling schools of fish at high speed, rolling the fish into compact balls then turning on their right side to engulf the fish. Their symmetrical colour pattern may somehow aid in the capture of such prey.

They can consume up to 1,800 kg or 2 tons of food a day. As a baleen whale, it has between 260-450 fringed overlapping baleen plates hanging from each side of the upper jaw. The baleen on the left side of the mouth has alternating bands of creamy-yellow and blue-gray colour. On the right side, the forward 1/3 section of the plates is all creamy-yellow. 

Social Groups & Activity
Fin whales are most often found alone, but groups of 3-7 individuals have been sighted, and larger numbers or concentrations may occur in some areas at times, usually related to the food supply in a particular area

The fin whale's blow is tall and shaped like an inverted cone. They rarely raise their flukes as they begin their dive, and can dive to depths of over 500 metres (over 1,500 feet).

Reproduction
Adult males reach sexual maturity at about 6-10 years of age. Gestation is 12 months, and calves are believed to be born at 3-4 year intervals.

Calf length at birth is 5 to 6 metres and weight is usually around 1,800 kg or 2 tons. The calves nurse for 6-8 months and are weaned when they are about 10 metres in length. Little else is known about their mating habits.

Distribution

Fin whales are found in all oceans of the world. They may migrate to subtropical waters for mating and calving during the winter months and to the colder areas of the Arctic and Antarctic for feeding during the summer months.

Some more recent evidence suggests that during winter fin whales may be dispersed in deep ocean waters rather than only congregating in the polar regions.

Their speed, plus the fact that they prefer the vastness of the open sea, gave them almost complete protection from the early whalers.

With the development of modern whaling methods, aerial tracking and long-range vessels, the finback whales became easy victims. As blue whales became depleted, the whaling industry turned to the smaller, still abundant fin whales as a replacement. As many as 30,000 fin whales were slaughtered each year from 1935 to 1965.

The International Whaling Commission (IWC) placed them under full protection in 1966 beginning with the North Pacific population.

It is thought that present populations are about 40,000 in the northern hemisphere and 15,000-20,000 in the southern hemisphere.

Distribution Map

Fin Whale  Distribution Map

Various

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