Whales and dolphins are part of the Order Cetacea. From here, whales are divided into two sub- orders: those with teeth (Odontocetes) and those without teeth (Mysticeti). Whales without teeth instead have plates of 'baleen'- coarse grey bristles that are used to filter food out of the water. Humpback whales (Megaptera novaeangliae) are baleen whales, and are also known as ‘rorqual" whales because of the pleated skin grooves on their throats.
Each whale has around 300 baleen plates that hang vertically from their jaw. The edges of these plates are frayed (like bristles) and this is where food gets trapped during feeding. The ‘rorqual’ grooves on the throat of the whale expand like an accordion to allow huge intakes of water which is filtered back out through the baleen. Their primary prey is krill, plankton and small fish.
Baleen whales are characterised by having two blowholes to breathe with, and humpbacks also have the longest pectoral flippers of all whales, reaching up to one third of their body length. Humpback whales grow to approximately 15m long, and weigh between 27-45 tonnes (males are usually slightly smaller than females). The life expectancy of a humpback whale is around 40-50 years.
Body colouring in humpback whales ranges from all black to mottled black and white markings, with the belly area generally white. They may have clusters of barnacles on their bodies, often on their flukes. Humpback tail flukes are unique, with the markings on the underside (ventral) used in photo identification studies. Flukes can be up to 3.7m wide, and are often out of the water.
Migration and Breeding
During the summer months, the Southern Hemisphere population of humpbacks can be found in their feeding grounds near the South Pole. Each year this population migrates north to the sub-tropical coastal waters around Australia and the South Pacific islands where they mate and give birth to their young.
The northern migration begins around June, and the return trip starts around September. These migrations can be up to 6000km long, travelling at speeds between 5-14kph. Humpbacks travel in loose aggregations called pods, and most associations are temporary. The exception is the bond between mother and calf. An adult male will often escort a pod of returning mothers and calves.
The gestation period for humpbacks is 11-12 months, so mating and birthing occur in the same northern migration period. Females calve every 2-3 years, and calves stay with their mother for around 2 years. During the migration adults do not feed, instead living off their layer of blubber (fat). Calves feed off their mothers’ fat-rich milk, increasing their weight 5 to 8 times in its first 11 months.
Male humpbacks are the most vocal of all whales. Songs are intricate variations of squeaks and growls, can last for 10-15 minutes, and be repeated for hours. Songs are localised to certain areas and evolve over time. The sounds can travel up to 50km underwater, making it a possible means of communication. It is believed that songs may serve as a sexual display or as intimidation to other competing mating males, though this is not certain.
Humpbacks are aquatic acrobats, often putting on some spectacular performances. These are just some of the more common behaviours:
- Breaching: Humpbacks can launch their bodies high up out of the water (sometimes completely!), and then fall back down with a tremendous splash. Breaching is thought to be a form of communication as the resounding splash can be heard for several kilometres.
- The Blow: This is the first sign that whales are around! Humpback whales can expel their breath out at speeds up to 450kph and vapour can reach up to 5m high. As they have a double blowhole, the vapour can have a v-shape.
- Pectoral & Tail Slapping: Slapping may also be a form of communication. Pec slapping is a playful whack on the water with their elongated fins. Tail slaps may be a form of position marking, and should be interpreted as possibly aggressive because of the force of the tail.
- Spy Hopping: For short amounts of time, whales can raise their heads vertically out of the water until the eyes are exposed. This enables the whale to have a look around, especially at boats, and also to orient themselves with the shoreline during migration.
Whale Watching Guidelines
Whale watching is exciting and unforgettable. It must be remembered that although humpback whale numbers are slowly increasing, they are still considered as endangered. To take care that whales are not harassed or injured there are regulations that watchers must adhere to:
- A vessel cannot approach closer than 100m to whales, or 300m when three or more vessels are already within the 300m radius. If a whale approaches the vessel, the engines must be placed in neutral.
- An aircraft cannot manoeuvre any closer than 300m above an area within 300m of any whale.
- In Australia, swimming with whales is not permitted. However, if any person is swimming, snorkelling or diving and a whale enters the area, the person cannot actively approach the whale within a 300m vicinity.
Check out the western and eastern sides of LEI for prime watching spots! Feel free to ask staff for more information.
Happy Whale Watching!