Humpback whales

Pod of Whales

Description

 

Humpback whales are known for their dark backs and mostly white bellies, with bumps and knobs protruding out of its head and flippers. The grooves¹ on its neck and throat make the humpback whale especially recognisable. The term ‘humpback’ is derived from the small lump in front of their dorsal fins. Their flippers are around a third of their body length, and range from black to white colouring depending on each individual. Their scientific name, ‘Megaptera novaeangliae’, means ‘big winged’ and ‘New England’ respectively, which refers to when European whalers first encountered them. 

 

Humpback whales can grow to 15 - 18 metres long, weighing 40 tonnes. This is as big as a bus! A whale’s tail is composed of two flukes. The trailing edge refers to the inside ‘V’ shape of the tail, and the leading edge refers to the rest of the tail’s perimeter. Humpback whales have a serrated trailing edge leading to pointed tail fins. The colouring of each humpback whale’s tail and the distinctive nicks and bumps along the trailing edge are unique, and acts as a ‘fingerprint’ for scientists to identify whales. 

 

Humpback whales are famous for their beautiful and mysterious songs. These songs are a complex mixture of moans, cries, and other noises which scientists predict are used to communicate and attract mates.

 

Conservation Status

 

During the 1960s to 1970s, where the whaling industry was at its peak, the humpback whale population was reduced drastically. After the Commercial Whaling Moratorium (1985) was enacted, numbers have gradually stabilised. Humpback whales were removed from the threatened species list at the start of 2022, with their conservation status at Least Concern. However, many conservationists warn this delisting could be too early - humpback whales are still threatened by climate change, fishing boats, and pollution. Read more on threats below. 

 

Diet

 

Humpback whales are omnivores, eating small crustaceans like krill, shrimp, plankton and small schooling fish. Humpback whales are filter feeders. Prey is caught by lunging with an open mouth, scooping up both water and prey. The water is then filtered through their baleen plates, leaving behind the food which can be swallowed. Humpback whales often work together to feed, using their flippers, sounds, or a technique called bubblenetting. Bubbles are exhaled below the school of prey, trapping the food inside a wall of bubbles. The whales will then feed in the middle. This technique varies between humpback whales living in different regions of the world!

 

Habitat and Migration

 

During Summer, humpback whales remain in colder Antarctic feeding waters. Humpback whales have one of the longest migrations — every Winter, they take the long journey towards the warmer tropical waters closer to the equator for breeding. During migration, males will produce the songs mentioned earlier, possibly to attract mates or mark territory. Whilst in tropical waters, humpback whales will often swim close to shore, allowing annual whale watching activities.

 

Behaviour

 

Humpback whales are particularly acrobatic, making them favourites of whale watchers. They frequently breach, jumping belly first out of the water, then arching their backs and returning under the surface. Often, their flippers and fins will slap the water and make large splashes after jumping. Their hump near their dorsal fins is particularly visible when a whale arches its back as it breaches. When whales dive deeper from the surface, they curl forwards with their tail sometimes becoming visible above water. Humpback whales will sometimes jump nose-first out of the water, calling sky-hopping, as well as twist their lower body around above water and slap their tail down, called a peduncle throw.

 

Parenting

 

A humpback whale reaches maturity between 4 to 10 years, and will not stop growing until 10 years old. A Mother whale will be pregnant for approximately 12 months and will nurse their calf for a year. Mothers and their calves can appear to show ‘affection’ for each other by touching each other using their flippers and communicating via sound. 

 

Threats

 

Even though humpback whales are no longer recognised as vulnerable, they still face many human-induced threats that may reduce their numbers if not resolved. 

 

  • Climate change

 

A report released by the IPCC in 2013 stated that the ocean has absorbed 93% of excess heat produced by greenhouse gases. As a result, the ocean becomes warmer and aquatic ecosystems are negatively affected. The population of prey species, like krill and plankton, is diminishing due to ocean warming, leading to less food available for humpback whales and the rest of the food chain. Habitats are being destroyed — like coral bleaching occurring in reefs all around the world, and in our own Great Barrier Reef! This is devastating as 25% of marine species depend on coral reefs! As humpback whales rely on the seasonal temperature of the oceans for migration between feeding and breeding waters, ocean warming also affects the timing and distance of their migration, and can even limit their ability to reproduce and navigate. 

 

If we don’t act now to reduce global warming to 1.5 degrees Celsius, climate change will become a rapidly concerning threat towards not only humpback whales, but all marine life!

 

  • Noise pollution

 

With so much human activity in the ocean since Industrialisation, including fishing boats, tourism, and gas development, there has been an increase in unnatural underwater noise. 

Scientists have seen this noise pollution disrupting normal marine life behaviour. For humpback whales, noise pollution can interrupt their communication via songs, cause increased stress, and impede on feeding. 

 

  • Plastic pollution

 

Humpback whales can become entangled in fishing gear or other plastics in the ocean, and will be unable to break free, often having to swim long distances with the plastic wrapped around its body. This results in abnormal fatigue, limits their ability to feed and reproduce, and often leads to injuries that may cause death. 

 

  • Ship collisions

 

Humpback whales are also at risk of colliding with ships, especially as they swim closer to human settlements during Summer. These strikes can cause severe gashes, with some severe injuries killing the whales.