The humpback whale is probably the most familiar of the great whales. We hear their “songs” featured in nature music and we see their acrobatic behavioral displays in television commercials. Along California’s central coast, the humpback is known as a “summer whale” although they may be seen from spring through fall.
Color: The humpback’s body is black above and white, black or mottled below. The flippers are usually white on the lower surface. The color on the upper surface of the flipper varies. Humpbacks in the North Pacific usually have black on the upper surface. Humpbacks of the North Atlantic and Southern Hemisphere have mostly white on the upper surface.
Shape: Humpbacks are rather stocky, with a broad flat head. The head and lower jaw have knobby protuberances called tubercles. The flippers are long and narrow and are approximately 1/3 the length of the body. The scientific name for humpbacks means “big wing of New England,” referring to the long pectoral flippers and to the location where the species was first described.
Weight and length: Adult male humpbacks weigh around 25 tons and females around 35 tons. Calves weigh about 1500 pounds at birth. Adult male humpbacks average around 46 feet in length and females around 49 feet, although the largest recorded individual was 62 feet long. Calves are 13-15 feet long at birth.
Feeding: Humpbacks feed on krill and small schooling fish. They have between 270-400 baleen plates on each side of the upper jaw. Their baleen is usually black. Between 14-22 throat grooves, or ventral pleats, extend from the tip of the lower jaw to the navel, allowing them to expand and take in huge quantities of water and prey. The whales that have numerous throat grooves that expand while feeding are called rorquals. Other rorquals include the blue whale and the minke whale.
Breathing and diving: As in all baleen whales, humpbacks have a double blowhole. Their blow, or spout, is about 10-12 feet high and bushy in shape. Their breathing pattern is comprised of 4-10 blows at 20-30 second intervals. The average dive in the summer feeding grounds is less than 5 minutes, but in the wintering grounds the average dive is 10-15 minutes long.
Migration: Humpback whales make one of the longest migrations of any mammal. Some travel 5000 miles one-way during migration. They spend the spring through fall in feeding grounds at high and mid-latitudes. Mating and calving occurs during the winter months spent in tropical or sub-tropical waters. They are usually found in coastal or continental shelf water, although some pass through deeper water while migrating. There is one population of non-migratory humpbacks in the Arabian Sea.
Sounds: One of the most intriguing behaviors of humpbacks involves the long complex songs performed by the males. Most of the singing occurs on the breeding grounds and is presumed to be associated with mating. Most songs last from 10-20 minutes and are repeated over and over again for hours. The songs vary between populations and change over time. In other words, the song produced by the humpbacks in Hawaiian waters is different from the song of the humpbacks in the West Indies.
Reproduction: In late fall the hormone levels in both males and females changes, signaling the approaching breeding season. Males may begin singing and may even begin competing with each other. As the migration commences, the cooperative nature of the summer feeding season changes to one of competition among males. On the breeding grounds males compete aggressively for access to females. Fighting can go on for hours and include ramming, tail slashing, and head butting.
Longevity: Humpbacks may live 50 years.
Predators: Scars from the teeth of orcas (killer whales) are seen on humpbacks, but it is believed that young calves are most likely to be fatally wounded. Sharks may also be a predator.
Distribution: Humpbacks are found in all the world’s oceans. In the North Pacific there are 4 different breeding grounds and 4 respective feeding areas. Crossover between these groups may occur. In the Southern Hemisphere there are 6 recognized populations, but it is likely there is some movement between these groups. In the North Atlantic humpbacks from 7 different feeding grounds all migrate to the West Indies to calve and mate.
Status: Humpbacks were an easy target for whalers because they are slow swimmers and are found close to shore. It is believed that more than 90% of some populations were wiped out during the most intensive whaling periods. During the last century about 200,000 were killed in the Southern Hemisphere alone. Commercial whaling ended in 1966. Some aboriginal hunting is allowed and some whales die as a result of becoming entangled in fishing nets or after colliding with ships. They are considered to be an endangered species, but their numbers are increasing. Today most populations appear to be making a comeback.
Other rorquals seen from Piedras Blancas:
The blue whale is thought to be the largest animal that ever lived, larger than any dinosaur, and yet they eat one of the smallest creatures – krill (a tiny shrimp-like crustacean.) On the summer feeding grounds, one blue whale may eat 4 tons of krill in a day! The average blue whale is 75-85 feet long and weighs 100-110 tons. Females are larger than males and may grow to a maximum of 100 feet long and weigh 150 tons. The comparisons are staggering. An adult blue whale is the size of 30 elephants. The tongue, alone, weighs as much as one elephant. Three buses put end-to-end would equal the length of a blue whale. Or, put another way, they are the size of a 737 aircraft. Blue whales are long, tapered and streamlined. In color they are light bluish-gray and have a mottled appearance. The dorsal fin is small and curved, located far along the back. They are fast, powerful swimmers. The blows are straight and tall reaching up to 30 feet – not like the bushy blow of the humpback or gray whale. Blue whales usually travel farther out to sea than gray whales or humpbacks, but they are occasionally seen traveling relatively close to shore, around Point Piedras Blancas. Blue whales are considered an endangered species.
The minke whale is the smallest member of the rorqual family. Minke whales have a dark, curved dorsal fin and do not show their flukes before a dive. The blow is low and bushy, usually not visible. They are black or dark gray above and light underneath. A white patch across the front flippers is distinctive. Males average 26 feet long and females average 28 feet. They are fast swimmers and may travel alone or in small pods. They are widely distributed throughout the world and may be seen off Piedras Blancas, however, they can be difficult to observe. One of their nicknames is “slinky minke” in reference to their erratic swimming pattern. You may see a glimpse of their flukes then nothing, only to see another glimpse far way from the previous position. You are unlikely to see their blow, especially in choppy water, and they do not show their flukes. Minke whales are hunted by Japan and Iceland for “scientific” purposes.
Background photo by Howard Hall, NOAA