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Home / News / General / Hawaii’s cetaceans

Hawaii’s cetaceans

By: Denver Leaman

Humpback whales






Humpback Whale (Megaptera novaeangliae)
Suborder: Mysticeti Family: Balaenopteridae
Common in Hawaiian waters during the winter season.
State mammal of Hawaii.

Other known names:

Hump-backed whale

General description and habits:

Humpbacks are one of the easiest species for researchers and whale watchers to identify. Their flippers may be as much as one-third of their total body length. Their knobby heads are also unmistakable. They have 12 to 36 throat grooves that expand when the whale is feeding using baleen instead of teeth. Individual humpbacks are recognized by the distinctive pattern of black and white markings on the underside of the tail fluke that is visible when they dive. These patterns are as unique as a fingerprint and enable researchers to keep track of individual whales. Adults measure 11.5 - 15m (38 - 49.5ft) with newborn whales measuring in at 4 - 5m (13 - 16.5ft). Adults reach 25 - 30 tons while newborn whales weigh 1 - 2 tons. Humpback whales entertain whale watchers by breaching; spy hopping; lob tailing and flipper slapping. Humpbacks are the most popular whales on whale watch trips, and probably create more great photo opportunities than any other cetacean species. Their dives usually last less than 10 minutes but can be up to 45 minutes long. Males can be quite aggressive towards each other during the breeding season.

Identity keys to use in the field:

Knobby head, Two blowholes, Throat grooves, Very long white and/or black flippers, Body mainly black or gray, Stubby dorsal fin, Tail flukes raised before deep dive, Wavy edge on back edge of tail fluke.

Diet:

Fish, krill and other crustaceans.

Distribution:

Humpbacks are found in all the oceans of the world but their distribution changes with the seasons. As a rule, most humpbacks migrate from their summer feeding grounds in polar regions to winter breeding areas in warm waters nearer to the Equator. Northern hemisphere populations never meet southern hemisphere populations. The worldwide population is divided into various stocks (one stock on either side of both the North Atlantic and North Pacific, and seven in the Southern Hemisphere) with little or no interchange between them.

Population estimates:

In the past more than 100,000 humpbacks were killed for their oil and they are now an endangered species and are protected under federal and international laws. There are currently about 7,500 humpbacks in the North Pacific population.

Threats:

Habitat loss, Chemical pollution, Noise pollution, Entanglement in fishing nets, Prey depletion (lack of food) .

Interesting facts:

The humpbacks that feed in Antarctic waters, south of Cape Horn and travel north to breed off Colombia and Costa Rica, make the longest confirmed migration of any mammal. Humpbacks, like other baleen whales, are filter feeders, and they have developed a number of strategies for feeding. One or more humpbacks may herd a shoal of fish into a cluster and then lunge with mouths wide open, gulping huge mouthfuls of water and prey. Seawater is forced out through the baleen plates, trapping the food behind. Humpbacks also create a kind of fishing net by exhaling air in a spiral of bubbles. Fish cluster tightly inside these bubble nets. All the whales have to do is to swim upward through the net with their mouths open. Male humpbacks sing the longest and most complex songs in the animal kingdom. These songs are a complex series of whistles, squeals, grunts, groans and wails divided into verses or themes that are sung in a specific order and may last for half an hour. Males in the same area sing the same songs, which change over time. It is believed that song is one of the ways males competing to attract females. Humpbacks have the longest pectoral fins of any cetacean. The tubercles, or bumps, on a humpbacks fins and head may reduce drag and increase lift, helping the animal to make tighter turns when chasing prey. Each tubercle is topped with a hair.

Migration:

During the summer these whales feed in the northern Pacific Rim, along the coasts of eastern Russia in the west and Alaska in the east with probable mixing between the two. During the winter months, humpbacks in the North Pacific breed around some of Japan's southern islands, the Hawaiian Islands and along Mexico's western coast. The majority of the whales go to Hawaii.

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Hawaii’s cetaceans
  • Humpback whales
  • Striped Dolphin
  • Spinner Dolphin
  • Baird’s Beaked Whale
  • Pacific Bottlenose Dolphin
  • Blainville's Beaked Whale
  • Bryde's Whale
  • Cuvier's Beaked Whale
  • Dwarf Sperm Whale
  • False Killer Whale
  • Fin Whale
  • Killer Whale
  • Melon-headed Whale
  • Minke Whale
  • Northern Right Whale
  • Pygmy Killer Whale
  • Pygmy Sperm Whale
  • Risso's Dolphin
  • Rough-toothed Dolphin
  • Short-finned Pilot Whale
  • Sperm Whale
  • Spotted Dolphin

     

     

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