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Blue Whale Fact Sheet

Blue Whale
Balaenoptera musculus

New York Status: Endangered
Federal Status: Endangered


Drawing of a Blue Whale

With lengths up to 100 feet (30 m) and weights up to 150 tons (136 metric tons), the blue whale is the largest animal that ever lived on this planet. An average individual is 70 feet (21 m) long and weighs 100 tons (90 metric tons). The female, which is larger than the male, gives birth to a calf that averages 25 feet in length and weighs about 2 tons. The calf drinks about 106 gallons of milk every day. An average adult has almost 2,500 gallons of blood and burns up to 3 million calories a day. Its heart weighs more than a ton and the tongue alone weighs about 2 tons! Linnaeus must have had his tongue in his cheek when he gave this species the Latin name "musculus," which means "little mouse."

As the common name indicates, the upper parts of the body are mottled blue-gray. The undersides are whitish or light yellow. This whale has a relatively small dorsal fin and black baleen plates. The straight, column-like water spout can reach 20 feet into the air. Speeds of up to 23 miles per hour (20 knots) have been recorded for the blue whale.

Life History

Blue whales migrate several thousand miles to wintering grounds and fast for the duration of their stay; the fat on their body is enough to see them through the whole winter. The mating season occurs for 5 months over the winter. A single calf is born after a gestation period of one year. It nurses for 7 months and will reach sexual maturity at 5-15 years of age. Females give birth every 2-3 years.

Distribution and Habitat

Blue whales are found in open oceans from the icy waters of the extreme Southern Hemisphere to the Aleutian Islands off Alaska at the northern boundary of the Pacific Ocean. Summers are spent in polar waters because food production is higher there. The diet consists exclusively of krill. In the winter, this species migrates to warmer tropic and subtropic areas to breed and calve.


The blue whale is currently one of the world's most endangered whales. It was not hunted until somewhat modern techniques made them more easily attainable, but by the mid-1900's only about 1,000 were estimated to remain. Hunting ceased in 1967 and stocks in the Southern Hemisphere and North Pacific are currently recovering. The latest estimate revealed 15,000 blue whales remaining worldwide. Pre-whaling populations were estimated at perhaps 300,000 individuals.

Management and Research Needs

Today, threats to blue whales include destruction or modification of habitat. They are protected by the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973. They are also fully protected by the International Whaling Commission. Efforts are being made to aid any whales which may become stranded offshore or washed up on beaches. A stranding network operated on Long Island by the Riverhead Foundation for Marine Research and Preservation under contract to DEC serves to alert marine biologists to the possible rescue of live animals and the identification and autopsy of carcasses. The hotline number for reporting strandings is (631) 369-9829.

Additional References

Katona, S. K., V. Rough and D. T. Richardson. 1983. A field guide to the whales,porpoises and seals of the Gulf of Maine and eastern Canada. Charles Scribner's Sons, New York. Pp 63-68.

Leatherwood, S., D. K. Caldwell and H. E. Winn. 1976. Whales, dolphins and porpoises of the western North Atlantic -- a guide to their identification. National Oceanic and Atmospheric Administration, National Marine Fisheries Service NOAA Tech. Report NMFS CIRC-396, Seattle, Washington. pp 19-25.

Leatherwood, S. and R. R. Reeves. 1983. The Sierra Club handbook of whales and dolphins. Sierra Club Books, San Francisco. 320 pp.

Drawing by Elane Eckert

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