Humpback Whales

The humpback is a large baleen whale that ranges from 12-16 meters (38-50 feet) in length and weighs approximately 36 tons. They are found in all the world’s oceans. They usually follow a migratory pattern of feeding in cold water and breeding in warm water.

The scientific name of the humpback whale, Megaptera novaeangliae, means long-winged New Englander. The “long wings” of the humpback are its pectoral fins. They are the longest in the world and can measure over 4 meters (12 feet) in length.

Why Humpbacks?

The humpback’s large size, overall abundance, and relatively slow swimming speed made them a favorite among 19th and 20th-century whalers. This occurred only after the slower moving Right and Bowhead whale populations were decimated, and the Atlantic Grey whale was driven to extinction.

By the 1970s, some jurisdictions considered humpback whales to be an endangered species. Today in most parts of the world, the cessation of whaling has contributed to a remarkable recovery in humpback numbers. Their ability to pursue a wide variety of prey items and their relatively prolific rate of reproduction resulted in a fairly rapid population recovery as compared to whales like the Atlantic right whale.

Humpback whales are regularly sought out by whale watchers and whale scientists because their laid-back, approachable, and entertaining nature makes them easier to study than most other species. They’re famous for their acrobatics, especially breaching (leaping out of the water) and for the complex, haunting whale songs that spawned centuries-old tales of sirens and ghosts in the ocean. Additionally, distinctive color patterns on the underside of the tail allow scientists to track individual animals and develop reliable population estimates.

Diet

Atlantic humpbacks live on the huge biomass of fish and krill found in temperate and subarctic/arctic waters. They spend summers building their blubber stores for winter when they migrate to tropical and subtropical waters for breeding. Migrating humpbacks do not feed during the winter even though their breeding grounds teem with a vast diversity of fish and marine life.

Humpback whales have baleen plates instead of teeth. The plates are made of mineralized keratin and hang from the upper jaw. Their fringed and overlapping structure is perfect for through enormous amounts of water to leave only food behind.

A common method humpbacks use to collect food is bubble net feeding. They create huge vertical columns of bubbles to disorient and corral prey into one area. They lunge through the area with wide open mouths to collect their prey. Next, they press their tongues against their baleen to filter out the water and swallow the food.

Physical Appearance

Humpback whales are black with white undersides and white markings on their pectoral fins and tails. Northern hemisphere humpbacks are darker and have fewer white markings than Southern hemisphere populations.

Flukes (whales tails) are unique enough that humans use them to identify and track individual whales. They have a serrated edge, white natural colorings, and very often have scars from orca bites or other traumas. Ridge patterns along a humpback’s backside also serve as unique identifiers. Serious whale science contributors are encouraged to collect both fluke and back images. The ability to identify individual humpbacks allows scientists to track migration and population changes.

 

Predation

Orcas and sharks are the main predators of humpback whales. Smaller and younger calves, or sick and distressed adults are the whales most frequently targeted. Though mothers fiercely protect their calves, pods of killer whales hunting together can succeed in separating calves from their mothers. Most of the orcas that prey on humpbacks are transient populations rather than resident orcas.

Shark species that prey on humpbacks include the great white and tiger shark. Sharks will attack whales up to three times their size, biting them until they bleed out or can no longer swim.

Humans were the largest predator of humpbacks, hunting their populations nearly to extinction. Whale hunting finally became illegal in 1986, but still occurs in some countries and in remote locations.

Distribution and Migratory Habits

For humpbacks in both the southern and northern hemispheres, summers are for feeding and winters are for breeding. Humpbacks in the Atlantic migrate up to 5,000 miles twice per year. At distances of over 100 miles per day, a 5,000-mile journey can take more than six weeks to complete.

In the North Atlantic Ocean, the planet’s largest gathering of humpback whales calls the waters off Newfoundland and Labrador their home from June to September. Some of the deep bays in this region have humpbacks that remain during the winter to pursue herring and other marine prey. The humpbacks that stay over winter are likely females taking a break from breeding.

In late September, most of the humpbacks leave their north Atlantic feeding grounds for their seasonal migration. They swim thousands of miles south to the warmer waters off the Caribbean and Dominican Republic, Azores, and the west coast of Africa. Here from October through late April, they use the warm tropical waters to mate, calve, and nurse their young.

SEE: North Atlantic Humpback Migration Map (opens in new tab)

In contrast in the South Atlantic Ocean, Southern Atlantic humpback populations spend November through March (summer in the southern hemisphere) feeding in the waters off of Antarctica. They migrate north to breed, spending July through October in their breeding grounds closer to the equator.

The wide distribution and differing migratory habits of humpback populations mean you can see humpback whales somewhere at almost every time of year.

Courtship and the Song of the Humpback

It is within the warmer southern waters where the males sing their impressive 20-minute songs designed to impress females. Mating behaviors sometimes get more vigorous as males jostle for closeness to the females, but the songs of the male humpbacks are remarkable for their complexity and variety. People today believe these songs inspired the legends of the Sirens from thousands of years ago.

Reproduction and Life Cycle

Humpback whales become reproductively mature when they are between 4 and 8 years old. The North Atlantic humpbacks breed in the Caribbean in places like the Silver Bank Whale Sanctuary off the Dominican Republic. It is here that females give birth to their four meter (13 feet) long calves. At birth, calves weigh about two tons and grow rapidly. The mother feeds her newborn about 40kg (100 lbs) of milk each day. Calves nurse for a period of five to seven months before they are weaned. After weaning, the calf has doubled its length and increased its weight five times, attaining a size of about 5 meters (26 feet) and 10 tons.

Usually, a female humpback bears one calf every two or three years. Many of the humpback whales that overwinter off the Newfoundland and Labrador coast are likely females taking a break from the rigors of reproduction. Scientists estimate that wild humpbacks have an average life span of 30 – 40 years, but no one knows for sure.

Ecological Importance of Humpbacks

Humpbacks have been likened to the canary in the coal mine – they are important indicators of oceanic health. Their ease of study, relative to other whales, makes them one of the best global indicator species for following the health of our oceans. If our blue planet cannot support humpbacks, then the humans who have depended on the oceans since they spread out from Africa millions of years ago will also be in trouble.

Threats

Vessel traffic, entanglement, and climate change are the greatest threats to humpback whales. Vessel traffic is high near coastal waters where humpbacks spend much of their time. Humpbacks are always at risk of injury or death by vessel strikes. Increased vessel traffic such as recreational and whale-watching boats can cause stress and behavioral modifications in whales. It is imperative that whale watchers and tour operators practice ethical whale-watching behaviors.

Entanglement in fishing gear is an ongoing threat to most whale species, and humpbacks are no exception. Entangled whales that can still swim will travel long distances with attached fishing gear. The added weight and drag of the gear results in fatigue, compromised ability to feed and reproduce, injury, and death.

Humpbacks are impacted by climate change because they rely on food that is directly affected by it. Small fish and krill populations, as well as plankton and algae are all hypersensitive to shifting sea ice coverage. Minute changes in both water currents and temperatures affect the navigation and migratory habits of humpbacks. All of these small changes add up to larger shifting patterns in foraging, nutrition, and reproduction.

Protections and Status of Humpbacks

All whales are protected by the Marine Mammal Act of 1972, which protects marine mammals in United States waters. Additionally, there are four humpback populations worldwide that have extra protection through the Endangered Species Act. In the Atlantic, this endangered population has its breeding grounds off the coast of Northwest Africa in the Cape Verde Islands.

Two more endangered populations are off the west coast of Central America and in the Western North Pacific off the coast of Asia. These two populations are both in the Pacific Ocean. Finally, there is the Arabian Sea population in the Indian Ocean, which lies between India and the Middle East.

You can view the full list of endangered species on the National Oceanic and Atmospheric Administration website. Choose ‘whales’ in the Species Category dropdown to filter results.