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Whales

Whales of the Great Barrier Reef

The Great Barrier Reef World Heritage area is home to around 30 different species of whale and dolphin. The most commonly sighted whales species are the Dwarf Minke and Humpback whales.

Minke Whales

Where do Minke Whales fit into the whale family tree?

The minke whale is the smallest baleen whale with 50-70 throat grooves. It is a rorqual whale (baleen whale with throat grooves). They are the most abundant baleen whale (world wide population estimated to be close to 800 000). Minke whales have a characteristic white band on each flipper, contrasting with its very dark gray top color. They have 2 blowholes, like all baleen whales. Other baleen whales are humpbacks and right whales.

What do Minke whales feed on?

Minke whales (like all baleen whales) are seasonal feeders and carnivores. They sieve through the ocean water with their baleen. They filter out small plankton, krill and small fish, even chasing schools of sardines, anchovies, cod, herring, and capelin. They have the same diet as blue whale (largest member of the baleen whales). The baleen plates in the minke whale’s jaws have about 300 pairs of short, smooth baleen plates. The largest plates are about less than 30 cm long and 13 cm wide. The fine textured baleen bristles are fringed and are creamy-white with pure white bristles.

Where do dwarf minke whales fit in to the picture?

Dwarf minke whales were first recognised as a distinct form in the mid 1980s and there is still little known about them. They attracted attention in northern Great Barrier Reef waters because they are naturally inquisitive, and often come close to boats and swimmers.
The dwarf minke whale is known only from the Southern Hemisphere. It has a white shoulder and flipper base, with a dark grey tip on the flipper. Unlike the Antarctic minke whale, it has a large dark patch extending onto the throat. Female dwarf minkes are on average about two metres shorter than Antarctic minkes (in baleen whales, the female is larger than the male). The largest dwarf minke whale that was accurately measured was 7.8 m long; adults weigh 5 to 6 tonnes.

Dwarf minke whales are most commonly seen on the outer reefs of the Great Barrier Reef between the months of March and October, with the best viewing time being the June to July period.

A new tourism industry has developed in recent years, where permitted operators take tourists out to specifically swim with these animals, based on voluntary approaches by the whales. Marine biologists are focusing their research efforts on why dwarf minke whales conduct these interactions. The bottom line is – don’t swim to the whale, let the whale swim to you!

Humpback Whale

Humpback whales regularly migrate from Antarctic waters along the east coast of Australia every winter. They can be seen on the GBR between the months of June to September. They annually migrate to warmer waters to mate and give birth. These giant leviathans are found in both hemispheres, but rarely (if ever) cross the equator, creating 2 different races. Their numbers along the East coast of Australia were decimated for about 100 years, but whaling was stopped in 1962 (more so from the industry being unviable than any government intervention!). Since that time, numbers have steadily increased.

Humpback whales are easily identified by having extremely large pectoral fins (their scientific name is Megaptera, which literally means giant wing!), and scalloped flukes.

Male humpbacks produce “songs”, which are believed to attract females at mating times (although there have been records of songs in summer, the non breeding season). The songs comprise a magical mix of clicks, moans and eerie wails. These songs can have distinct patterns, and can last for over 20 minutes, with the whale only pausing to take a breath. The same song will often be repeated for hours on end. Females are not known to vocalize.

Humpbacks can display a wide range of behaviour, such as:

Tail slapping: This is where they slap their tail on the surface. It can be a form of communication, but more often then not it is an aggressive display.
Spy Hop: Humpbacks will often surface vertically, and actually stick there head out of the water so that they can see above the waterline. There is nothing like being eyeballed by a 15m whale!
Bubble Netting: A technique developed to allow whales to entrap their prey (krill) by creating a ring of rising bubbles. The whale then moves through the net and uses it’s baleen to trap the prey.
The Blow: Often the first indication that a whale is in the area. The vapour cloud produced is caused when the whale empties its lungs, and can be quite pungent if you’re downwind!
Breaching: The most spectacular display of all, where the animal leaps almost clear of the water, creating the kind of splash that only a 40 tonne animal can produce!