HUMPBACK WHALE FEEDING
Bubble net feeding Humpbacks are generalized, highly mobile and opportunistic feeders. They can feed upon plankton at the surface of the ocean or feast on schools of fish, typically filter-feeding krill and small fish, typically consuming one or several US tons of food per day during the feeding season. They like to feed on schools of herring. In some places they are joined by huge masses of shearwaters and other sea birds that feed on the same prey the whales do. Humpbacks appear to only feed in their old-water feeding areas. Humpback whales use several "tools" to help them herd, corral, and disorient prey, including: bubbles, sounds, the seafloor, and even pectoral fins. [Source: NOAA]
Humpbacks have up to 800 baleen plates on their upper jaw. When feeding, Douglas Chadwick wrote: "The lower jaw swings out from the upper jaw to open at a 90-degree angle, or even wider; one to three dozen grooves, or pleats, on the throat expands; and what was a sleek becomes a living vat swollen by as many as 15,000 gallons of water churning with fish."
Websites and Resources: Humpback organizations and experts: the Maui-based Whale Trust; Lou Herman of the Honolulu-based Dolphin Institute has published more than hundred papers on humpbacks, their songs, their migration patterns, and interaction between mothers and calves. Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures
Humpback Whale Feeding Behavior
Humpback lunge feeding During the summer months, humpback whales spend most of their time feeding and building up fat stores (blubber) to sustain them throughout the winter. They migrate thousands of miles round trip and spends months in calving and mating areas, apparently eating little or nothing at all, living off the blubber they built up during their months of binge eating at the feeding grounds.
Humpbacks in different places eat different kinds of food. Those near Australia and in the Antarctic feed main on krill. Fishes comprise about 95 percent of the diet of North Atlantic humpbacks. Those humpbacks living in the Atlantic Ocean, specifically near Cape Cod and Greenland, also eat sand lance, herring and pollock. Atka makerel and Pacific saury are the most commonly found fish prey of humpbacks in the eastern North Pacific Ocean. The former is considered one of the favorite foods of humpback whales in waters off the Western Aleutians and South of the Amchitka Islands. In addition, humpbacks in the North Pacific and the Bering Sea eat euphausiids (krill), mackerel, sand lance, Ammodytes americanus, capelin and herring. /=\
A study published in 2021 found that off the U.S. West Coast humpback whales eat 5 to 10 tons of krill or 2 to3 tons of fish each day, compared 10-20 tons of krill daily for blue whales and 6-12 tons of krill daily for fin whales. They study found that the whales primarily feed at depths of 165-820 feet (50–250 meters). [Source: New York Times]
Humpback Whale Feeding Methods
Humpbacks are classified as "swallowers" not "skimmers." Typically, they take both food and water into their mouths. Large volumes can be accommodated because the ventral grooves in the throat expand. Once the mouth is full, it is closed and with the help of the giant rorqual tongue the water is pressed out and the food is caught in the baleen plates and is then swallowed. Humpbacks often feed by swimming toward drifting masses of krill and suddenly lunging forward and trapping the prey. "Pleats in the ventral pouch beneath their lower jaw unfold as the whales surge ahead with their mouth wide open." It is estimated that a humpback can hold 15,000 gallons of water at one time. [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
One method of humpback feeding is called lunging. This involves swimming vertically or obliquely through aggregations of plankton or fish. This occurs mostly when their food is abundant. In addition, some variation may occur by means of lateral and/or inverted lunging.
A whale employing tail slashing swims in a large circle through the water while slashing its tail. The actual feeding takes place in the center of the turbulence. Inside loop behavior involves making a shallow dive, while hitting the water with its fluke as it submerges. A 180 degree roll is then rapily executed as the animal makes a sharp U turn (the "inside loop") and then lunge feeds slowly through the turbulent area created by its flukes. The whale feeds beside the area of turbulence. Flick-feeding is employed when humpbacks eat krill.
No humpback younger than two years old have ever been observed using the tail slapping method, although they are weaned from their mothers at one year. This implies they are taught the technique when they are older. Rudimentary lobtail feeding has been witnessed several times among older post-weaning young. In addition, no difference has been noted in the frequency of lobtail feeding between the sexes. /=\
Humpback Whale Group Feeding
In areas where there is lots food, humpbacks often work together in coordinated groups of up to 25 or so to gather food. They often emit loud shrieking noise, raps their tails and eject huge masses of bubbles, and flap their flippers perhaps to confuses their prey or round them. They have frequently been observed herding fish or krill against a shore ore even forests of kelp, trapping the prey and gulping it down.
The Ring of foam is an elaborate humpback feeding behavior in which they lie on the ocean's surface and swim in a circle. While doing so, they strike the water with their flukes forming a "ring of foam," which surrounds their prey. Then, they dive under the ring and resurface in the center with mouth open, allowing them to capture the prey within the ring. [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW) /=]
Humpbacks also pound and herd prey with their flukes and flippers. A group of humpback in the Gulf of Maine not only envelope the fish in curtains of bubbles they also lift their flukes out of that water and bang them on surface, creating churning water that confuses the fish even more. The practice was first observed in 1981 and has the passed on to members of the community and from mother to offspring.
Scientists who make a living observing humpbacks say that groups often return to the same feeding grounds and use the same techniques — such as diving and surfacing in a group — over and over. It appears that groups that feed together are not part of family or social group but rather seem to be in the same area at the same times and decide to cooperate.
Humpback Bubble Feeding
One feeding method employed by humpback whale seen in Alaska waters and off British Columbia, called "bubble net feeding," involves using curtains of air bubbles to condense prey. Once the fish are corralled and pushed toward the surface, the whales lunge upward through the bubble net with open mouths engulfing their prey. Different groups of humpback whales use other bubble structures in similar ways, though, there appears to be regional “specializations” in bubble-feeding behavior among populations.[Source: NOAA]
Humpback blow a net-like ring of rising bubbles to concentrate and surround the fish, followed by open-mouth whales surfacing in the middle of the ring, gulping prey. Douglas Chadwick wrote on National Geographic, "The whales may lunge at the prey near the surface, plow down into their midst, or dive deeper and circle below the fish, blowing a ring or fizzing bubbles to act as a net, the rise up the center. Sometimes the animal blows different size bubbles depending upon on the size of its prey."
Bubble columns are formed as a humpback swims underwater in a broad circle while exhaling. An individual column may form rows, semicircles, or complete circles. These circles act like a sieve net, concentrating or herding the prey. Bubble clouds are large inter-connected masses that concentrate or herd a mass of prey. Feeding is presumed to occur underwater. After that the humpback rises slowly to the surface within the bubble cloud. After several blows and some shallow diving, the manuever is repeated. Bubble clouds appear to assist in prey detection or capture by immobilizing or confusing prey. Bubble clouds may cause a jumping response among the prey, helping the whale to detect the prey, or it may disguise the whale from the prey. Sometimes humpbacks combine bubble feeding and tail slapping (lobtailing) to feed feed fish such as on sand lance. [Source: Mindy B. Kurlansky, Animal Diversity Web (ADW)]
Orcas and Humpbacks Feast Together on Herring
In the fjords of Norway, humpback whales and orcas hang out together. with the humpbacks tending to follow the orcas and steal their bait balls. Reporting from there in winter, Clément Brun wrote: It was 2:30pm and the sun had already set. Right in front of me, a pod of orcas worked together to push a herring bait ball towards the coastline. At the shore, there was no easy escape for the fish. They became an easy target in the shallows. The fish were trapped in water that was less than 10 meters deep, surrounded by orcas who were soon joined by several humpback whales. [Source:Clément Brun, Oceanographic]
When the pod of orcas left the area after feasting on the bait ball, the humpback whales kept feeding. The underwater ballet-like movements of the humpback whales feeding and manoeuvring so gracefully in shallow depths and the mesmerising circling of the herring ball that looked like all the fish transformed into one single organism were breathtaking. The rocky bottom of the fjord added a sense of roughness to the scene.
When the humpbacks swam close to the school of fish, it looked as if they were flying with their distinctive white pectoral fins. They would slowly approach the bait ball, would speed up with their tail and lunge feed. On one of the images, we can clearly see the extended lower jaw right after the humpback had engulfed a large quantity of prey. After a few lunges, these true leviathans seemed to have had their fill and left the fish alone.
A significant part of the North Atlantic humpback whale population feeds in the Barents Sea during the summer months, a shallow shelf located to the East of the Svalbard archipelago and to the North of the Norwegian mainland. At the end of the feeding season, in the fall, these whales start their journey south towards the tropics where they gather to reproduce. Mainland Norway is thought to be a migration corridor for this part of the population between the feeding grounds in higher latitudes and the breeding grounds in lower ones.
Interestingly, while on their way to lower latitudes, some individuals delay their migration. They seem to prolong their feeding season to forage on herring that have been consistently overwintering in coastal areas of Northern Norway for the past ten years. Herring enter the fjord system in the fall and gather in large numbers in the region. The high density of herring might provide important additional energy for these humpbacks before they cross the Atlantic Ocean basin and reach their breeding grounds thousands of kilometers away.
But not all individuals decide to stop over and feed on herring. This suggests that some individuals might need this extra energy intake more than others. By looking at the size of the whales which do stop over here (they mostly are big whales) and deciphering very old whaling record data from around 100 years ago, it is thought that a large proportion of these humpback whales could potentially be pregnant females. Because they are not in a hurry to get to the tropics, they would take advantage of the herring availability in Norway before embarking on the rest of the migration.
These ‘winter humpbacks’ usually feed in the presence of orcas, a species that is known to follow the herring all year around in Norway. Although orcas belonging to this population occasionally feed on marine mammals, such as seals and harbour porpoises, herring constitute the main food source of their diet. During winter, the herring usually try to stay in the deep parts of the fjord to be better protected from predators. That’s why these encounters are so special — it’s absolutely fascinating to see humpback whales and orcas interacting with each other, while feeding on the same prey. After all, in other parts of the world, orcas are known to attack and feed on humpback whale calves occasionally.
Image Source: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated May 2023