SUMMER 23/24

KNOW YOUR WHALES on the ‘HUMPBACK HIGHWAY’
More than 40,000 whales make their way past the Central Coast on their migration north then back south on their return to Antarctic waters each May to November.

Share:

Along what is generally known as the Humpback Highway, the humpbacks and minke whales are the most commonly sighted but, if you’re far enough offshore, you may also spot orcas, blue whales, beaked whales, southern right whales and sperm whales that all prefer to travel closer to the edge of the deep continental shelf.

The southbound return journey from August to November is when you are more likely to see whales closer to shore, sometimes taking a break in bays with their calves, and teaching them the fundamentals of tail slapping and breaching. 

The good news is that the whale watching season is getting longer as whale populations rebuild.

HUMPBACKS

Humpbacks cover about 10,000 kilometres during their annual round trip at a leisurely speed of about three kilometres per hour.

Scientists thought whales fasted during their migration, only feeding again on krill and small fish once they returned to their Antarctic waters. However, rare groups of 20 or more whales have been observed on their southward journey, swimming in circles to create a perimeter of bubbles that herds schools of fish into their bubble ‘net’ so they can scoop them up for a communal feast. Scientists also get an idea of the whales’ health using specialist drones to collect whale breath particles after they breach and blow.

Humpback whale (PHoto: Chris Dick)

SOUTHERN RIGHT WHALES

Southern right whales were considered the ‘right’ whale for harpooning in the 1800s because they travelled close to shore and had a huge oil yield. They also floated when dead, making them easy to recover. They are a slow moving whale and, even today, collisions with ships are a major cause of death or serious injury for this species.

They are still listed as endangered, and in our immediate region of south eastern Australia their numbers have only increased to around 270 individuals. 

Southern rights are distinguished by the white/grey toughened skin growths, known as callosities, on their heads. The patterning of these callosities is unique and is used to identify individual whales. 

Their huge heads measure up to a third of their body length and their jaws hold around 250 baleen plates that hang down from their top jaw like an enormous curtain that they use to trap up two tonnes of krill and other small crustaceans a day. 

Weighing as much as eight adult elephants, southern right whales make an impressive sight off the coast but, given their small numbers, usually only a few are sighted in NSW each season. Although slow to breed, if they avoid shipping lanes, they can live up to 100 years.

Southern right whales (Photo: Chris Dick)

MINKE WHALES

Antarctic minkes and dwarf minkes are the smallest of the baleen whales (about the length of a double-decker bus) and may live up to 60 years. They are very inquisitive animals and the writer has personally experienced being surrounded by curious minkes (including a mother with calf) that repeatedly swam in circles around a group of snorkellers, turning on their sides to make eye contact and seemingly as curious about us, as we were about them.

The white and grey markings on the sides of a minke are unique to each whale, making for easy identification. 

Killer whales have an affinity for this little whale, and the minkes’ defence is a fast getaway speed of up to 30 km/h, making them among the fastest of all whales. And, apparently, the way to tell the age of a minke is to count the waxy layers in its ears – though this is probably not very useful information, given their speed. 

Minkes were named after a young Norwegian sailor who harpooned one, mistaking it for a much larger blue whale. He was never allowed to forget it!

Minke whale (PHoto: Chris Dick)

SPERM WHALES

Sperm whales are the largest of the toothed whales and their survival is listed as vulnerable. 

Males are the greater long-distance travellers, while females tend to favour warmer waters. They are known to migrate along the NSW coast where the continental shelf rises steeply from a great depth. Here, they feed mainly on squid, octopus and a variety of fish. 

Although they are deep divers, often staying submerged for up to 90 minutes, they also like to remain at the surface for extended periods of time making them easier to spot.

The sperm whale is the only whale with a single blowhole near the tip of the left side of its head and is readily distinguished by a narrow and underslung lower jaw and an extremely large head – up to 35 per cent of its total body length. 

They communally care for calves and demonstrate unusual altruism towards the injured or sick in their pod.

Sperm whale (Photo: Ocean Aimee)

ORCAS

Orcas, also known as killer whales or misguidedly as sea pandas, are considered one of the most efficient large predators in the ocean. They work in packs to hunt cooperatively to chase down or surround seals, penguins, fish, stingrays, dolphins, minke whales, and even blue whales.

They are also known to follow humpbacks on their southern migration, often preying on the newborn calves even in the presence of a protective humpback male.

Their ability to stay submerged for long periods has made them difficult for scientists to observe and knowledge about orcas’ lifestyle still has major gaps.

Orca hunting a beaked whale (Photo: Jan Hunter)

PILOT WHALES

Pilot whales are characterised by their round, bulging forehead and short beak-like snout. They inhabit the coast close to the continental shelf, but have also been found in deep, open ocean. There are two species, short-finned and long-finned pilot whales, with the former preferring warmer waters and the latter a colder environment.

They grow to around six metres in length, are black or dark grey in colour, sometimes with a pale, elongated anchor shape on their throat and chest.

Pilot whales are highly social and follow a leader – something that may explain why this species is often involved in mass strandings. They are called pilot whales as old, sailors’ myths told of them showing ships into a safe harbour during squalls and storms. Unfortunately, this also led many ships to their doom. 

Pilot whales (Photo: Montse Grillo)

BEAKED WHALES

Little is known of beaked whales because of their elusive behaviour, low population numbers, and because their natural habitat is the deep ocean. That said, Gray’s beaked whale is the second-most common whale species to become stranded on Australian beaches, so most information has come from beached whale carcasses. Up to 28 beaked whales at a time have become stranded which scientists believe may indicate how sociable they are. 

Beaked whales are named for their long, cylindrical ‘beak’ that protrudes as the whale surfaces. Adult males tend to be slightly buck-toothed, with large triangular teeth that grow 6 to 10 cm wide.

Beaked whales are also susceptible to bites from small cookie-cutter sharks, which as their name implies, leave circular bite marks that become white scars. Males also often carry tooth-raked scars thought to be from combat with other males.

Beaked whale (Photo: Karen Stockin)

WHALE SAFETY

Loud underwater noises such as seismic surveys drilling, pile driving, blasting, dredging, vessel noises and military sonar, can disrupt whale communication and deter them from following migratory paths or important habitats.

For the safety of both whales and humans, people must keep at least 100 metres from a whale, and 300 metres if a calf is present. Jet skis must always stay a distance of 300 metres.

WORDS CATHARINE RETTER AND RONNY LING – Central Coast Marine Wildlife Rescue and President of the Central Coast Dolphin Project. ccdolphins.org

Featured image of four humpbacks by Jonas Liebschner

Share:

More articles