Found throughout the world’s oceans, humpbacks migrate thousands of miles between their calving grounds in the tropics and the nutrient-rich cold waters where they feed. They can be found both inshore and offshore, but they tend to follow the coastlines, making them a popular sight for whale-watching expeditions. The humpback is social, sometimes hunting cooperatively, and is known for its feeding techniques: lunging through patches of fish and krill; stunning its prey with its flippers or flukes; and bubble-netting. In bubble-netting, the whale swims in a spiral below a shoal of fish and krill, expelling air and surrounding prey with nets of bubbles, facilitating an efficient catch as the whale swims up, open-mouthed, through the center of the bubbles. Humpbacks are generalist feeders that consume krill, copepods, and a variety of schooling fish. Only the male humpbacks sing their characteristic and complex songs while on breeding grounds, often for 10-20 minutes at a time. Living up to 50 years old, this whale usually reaches sexual maturity at nine, and females give birth to one calf every two years, usually between the months of January and April.
In the North Atlantic, approximately 10,000 humpback whales congregate in the West Indies to mate, calve and raise their young before heading to their northern feeding grounds, located off New England, eastern Canada, western Greenland, Iceland, and northern Norway. In the North Pacific, there are three relatively discrete populations totaling 4,000-7,000 whales. The Eastern North Pacific stock winters off the Pacific coast of Central America and Mexico and migrates to coastal waters of California and southern British Columbia. The Central North Pacific stock spends its breeding and calving seasons in the Hawaiian Islands and migrates to northern British Columbia, southeast Alaska and west to the Kodiak Archipelago. The Western North Pacific stock winters south of Japan and migrates to the Bering Sea and Aleutian Islands in summer.
Intensively hunted by whalers, the global abundance of the species is thought to be between 20,000 to 30,000 individuals—a mere fragment of estimated pre-exploitation population. Presently, populations are thought to be limited but relatively stable. While commercial whaling has been curbed, illegal whaling remains a threat. Entanglements in fishing gear are evident in the North Atlantic population. Ship collisions cause some mortality, and oil pollution, toxic chemicals, disease, and acoustic disturbance from sonar are on-going hazards. Dwindling food availability is a relatively new worry, especially in the greater Gulf of Maine/Georges Bank area. Disturbance by whale-watching tourists, especially in Hawaii and Alaska, may force humpbacks to abandon preferred habitats.