Bubble-net feeding

Bubble-net feeding is a special way that humpback whales and Bryde's whales catch food. They swim close to the surface of the water and blow bubbles to trap small fish and other food. This makes it easier for them to gather food quickly. Sometimes, many whales work together, with up to twenty whales doing this at the same time. Humpback whales also use another method called lunge feeding to catch their food.

Humpback whales move between different areas during the year. They only eat during half of the year, but when they do, they feed almost nonstop for up to twenty-two hours each day. This helps them build up fat for the time when they are ready to have babies and cannot eat at all. In the summer, they usually go to colder waters where they can find plenty of food, such as in Southeast Alaska and near Antarctica.

Method

Bubble-net feeding is a special way that groups of humpback whales work together to catch food. This behavior is something they learn, not something they are born knowing. Not all groups of humpback whales know how to do this.

When humpback whales want to catch small fish like salmon, krill, or herring, they work as a team. They make a "net" of bubbles to trap the fish. One whale starts by blowing bubbles from its blowhole at the fish. Then more whales join in, blowing bubbles while swimming in a circle around the fish. This bubble net can be as small as three meters or as big as thirty meters across.

One whale makes a special call, and then all the whales swim up together with their mouths open to eat the fish trapped in the bubbles. When they swim up, they can hold a lot of water in their mouths—up to 15,000 gallons! Humpback whales have special grooves on their chins that let their mouths stretch wide. When they swallow, they push the water out through their baleen and keep the fish.

Sometimes, a humpback whale hunts alone using a method called lunge feeding. The whale dives under a group of fish and comes up with its mouth open, then swallows the fish and pushes the water out.

Theories

Scientists have many ideas about how fish get caught in the bubble nets made by whales. One idea is that the sounds whales make when breathing out trap the fish. Inside the bubble circle, it is quiet, but outside the sounds are so loud that fish can’t escape.

There are also many theories about why humpback whales use bubble nets to catch food. The oldest records of this behavior date back to 1929 in the Norwegian Sea. Some thought it was just play between whales. Others think changes in the environment over time led to this method. The most common idea is that this way of feeding helps whales survive, especially after they were hunted a lot in the past. This method lets many whales eat quickly.

Diet

Humpback whales cannot eat anything larger than the size of a grapefruit because of their throat size. They are carnivores, which means they eat meat, and they mainly eat small fish like krill, young salmon, and herring. Since they do not have teeth, they are baleen whales and need to eat food they can swallow whole.

These whales have special grooves on their bodies that let them hold lots of water and fish at once. They can eat for up to twenty-two hours a day, consuming between 4,400 to 5,500 pounds (2.0-2.5 tons) of food daily. They only eat during the summer, using fat they stored to survive the winter. They cannot eat in warm places like Hawaii or Mexico because those areas do not have enough of the fish they need, but cooler areas like those near Southeast Alaska are full of food, making them ideal for feeding during the summer.

Setting

Bubble-net feeding is mostly seen in cold, sunny waters like those in Alaska, where the conditions help create plenty of food for humpback whales. Places such as Antarctica and the North Pacific also offer good feeding areas with lots of marine life. However, warmer areas like Mexico and Hawaii are more for breeding and do not have as much food for the whales, so they depend on the food they gathered during their feeding time.

Ecotourism

Humpback whales were listed as endangered since 1970 because of whaling, but their numbers have grown thanks to rules against whaling and the growth of ecotourism. Whale watching tours let people see these whales in the wild, which helps protect them. There are rules to make sure boats don’t bother the whales. Boats must stay more than three hundred yards away, and if a marine mammal comes close, the boat must stop its engine.

Bubble-net feeding has become a popular part of whale watching. It looks amazing and helps people learn about these whales. However, this behavior is rare and hard to predict. When it happens, the only sign might be a ring of bubbles on the water’s surface, and birds often gather nearby hoping to catch fish.

Even though humpback whales are recovering, there are worries that too many tours could disturb them. More people on the water can change how the whales behave, including how they feed. The noise from boats can also make it harder for whales to talk to each other and feed using bubble nets. Scientists are still studying these effects.