Blue Whale

Tagged: animal, cat, fish

Balaenoptera musculus It took fewer than 50 years of intensive whaling to bring the largest animal the world has ever known to the brink of extinction. Whether the remaining blue whale population is large enough to make a recovery remains to be seen. Humans have hunted whales for well over a thousand years, but it was not until the 1860s that new technology allowed whalers to hunt the largest species of all. Whaling in the late 19th century was difficult and dangerous; but by targeting the largest of the great whales, the whalers could reap enormous profits. Hunting for blue whales began in the North Atlantic; but as the populations there declined, attention turned to other oceans. In the early 1900s 90 percent of the world’s quarter of a million blue whales lived in the Southern Hemisphere. When these rich hunting grounds were discovered, whaling stations were established on small islands in the Southern Ocean. At first whalers had to operate close to coastal factories and could not fully exploit the whales that remained far from land. However, with the arrival of the first factory ships in the mid-1920s, they could process their kills on the open ocean, and consequently the death toll soared. By 1960 it became obvious that the blue whale was heading for extinction, but it was still several years before an international ban on commercial whaling was agreed. The intervening years cost the species several thousand more lives, bringing the total death toll to 350,000 in fewer than 70 years. After the killing stopped there were high hopes that the blue whales would recover. By the mid-1980s there was evidence of a slight increase in numbers, and surveys showed that pregnancy rates had doubled, from about 25 percent in 1930 to over 50 percent. The total world population was estimated at the time at about 12,000 individuals. However, the early optimism proved premature. Estimates vary as to how many blue whales there now are, but recent statistics put the world population as low as 3,500. It is doubtful whether so few whales represent a viable population.

Impoverished Oceans The main reason why the whales’ numbers have not recovered is simply because their habitat has altered for the worse. The annual catch of krill (planktonic shrimps) taken by the world’s fisheries rose from practically nothing in the early 20th century to over 500,000 tons (455,000 tonnes) in 1986. An average blue whale needs about 7,700 pounds (3,500 kg) of krill a day to sustain its great bulk. Now that krill is fished on such a huge scale, there may simply not be enough food to meet the whales’ requirements. The seas are also more polluted now, and not just with chemicals. Toxins and biologically active substances that have been shown to damage other marine wildlife almost certainly affect large whales. In addition, whales are affected by noise pollution and alterations in local currents brought about by coastal developments. Large inland projects can also result in thousands of tons of silt being dumped at sea, making the water unsuitable for both whales and their food. Blue whale (great northern rorqual, sulphur-bottom) Balaenoptera musculus

• Family: Balaenidae
• World population: About 3,500
• Distribution: Three separate populations: in the North Atlantic, North Pacific, and Southern Ocean respectively; the whales migrate annually between polar and tropical waters
• Habitat: Deep oceans
• Form: Vast, streamlined body; bluishgray skin with pale markings and white to yellow underside. Rounded snout;deep throat furrows; 2 blowholes with large splashguard; small dorsal fin set well back on body
• Diet: Krill (planktonic shrimps) and other crustaceans
• Breeding: Single young born after gestation of 10-12 months; weaned at 7-8 months; mature at 10 years. May live up to 110 years
• Size: Length: 79-89 ft (24-27 m); occasionally up to 110 ft (33 m); females larger than males.
• Weight: 110-132 tons (100-120 tonnes); occasionally up to 209 tons (190 tonnes)
• Related endangered species: Fin whale (Balaenoptera physalus); sei whale (B. borealis); minke whale (8. acutorostrata)

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