Whales

Fin Whale - Balaenoptera physalus

The Fin Whale, also called the Finback, Razorback or Common Rorqual is the second largest living animal and second largest whale after the Blue Whale, growing to some 27 meters. There are two distinct subspecies of the Fin Whale, one being the Northern Fin Whale of the North Atlantic, and the other larger Antarctic Fin Whale of the Southern Ocean. This species are found in all the world's major oceans, from both polar to tropical waters. Its body is long and slender, brownish grey with a paler underside in appearance. A mature adult has never been weighed, however, calculations suggest that a whale measuring 25 meters could weigh as much as 70 000 kilograms. It has a pointed snout and paired blowholes. They are known to live to 94 years of age.

The Fin Whale has a number of pleats or groove that run along the bottom of its body that allow the throat to expand greatly during feeding. Its diet consists mainly of fish, squid and crustaceans. While swimming at relatively a high speed of approximately 11 kilometers per hour, it feeds by opening it jaws and engulfing up to 70 cubic meters of water in one gulp. Each gulp provides approximately 10 kilograms of krill. It has been said that one whale can consume up to 1,800 kilograms of food a day, spending three hours of each day meeting its energy requirements. They have been seen to circle schools of fish at high speed, compacting them into a small area, then turning onto its side before engulfing them all.

When the whale surfaces, the whale will possibly blow one to several times, staying close to the surface for about one and a half minutes on each occasion, with the remaining submerged. It dives to depths of up to 250 meters, with each dive lasting between 10 and 15 minutes. Fin Whales have been known to leap completely out of the water. Male Fin Whales make long, loud, low-frequency sounds, together with the Blue Whale, these whales make the lowest known sounds made by any animal. Each sound lasts between one and two seconds, with different combinations of sounds occurring in patterned sequences which could last 7 to 15 minutes each. These vocal sounds can be detected hundreds of miles from their source.

Calving occurs mainly in winter from April to August, with gestation being 11.25 months. Females bear offspring at an interval of 2 to 3 years and nurse their young for 6 to 7 months. Sexual maturity starts from approximately 6 to 10 years of age and at 19 meters in length. Hybridisation between fin and blue whales has been documented on five occasions, of which all were taken in for commercial whaling operations in the Northern Hemisphere.

Studies on fin whales have shown that they carry pollutants such as organochlorine and heavy metal compounds which accumulate with age and are transferred during lactation. These pollutants are known to cause reproductive and health impairment even in other species of marine animals.