The Sydney whaleways: it’s cetacean migration season!
By Alec Smart
Photo: Daniel Ross / Pexels
The annual whale migration season is in full flight, as an estimated 40,000 cetaceans make their way up the east coast to warmer waters for feeding and breeding.
Between early May until late August, whales journey northwards through the Tasman Sea to the Coral Sea, and out into the South Pacific Ocean, many of them in close proximity to the shore.
From mid-August until late November the cetaceans return; the early southbound travellers on route to the Southern Ocean bypass the late northbound, often socialising as they cross paths.
Humpbacks, which feature distinctive fluted chins and long fins with up to 11 bumps known as ‘tubercles’, are, along with southern right whales, the most common of the migratory cetaceans in our waters. Around 30,000 (of the approximately 80,000 humpbacks worldwide) travel up and down the east coast of Australia every year.
Humpbacks and grey whales travel the longest distances of all whales – some swim a 10,000km round trip during their migratory cycle! Males often leap completely out of the water - known as ‘breaching’ - during demonstrations of strength generally intended to impress females.
Humpback whale 'breaching'. Photo: Andre Estevez / Pexels
However, only a few species of dolphins migrate, often travelling in pods among the whales, and they trek significantly shorter distances, preferring instead to follow the seasonal movements of their favourite fish prey.
Whales frequently pause to rest or socialise in bays and sheltered coves during their migration.
Bondi, for example, receives occasional visitors.
On 24 June 2023, a kayaker on an early morning paddle was escorted to shore by a 5-metre humpback whale that swam alongside, the incident captured on aerial camera by DroneShark and posted to their social media page.
On 6 June 2023, a small pod of around six whales were filmed frolicking in the bay. On 31 May 2022, curiosity got the better of two young humpback whales that swam in to closely inspect a group of three ocean swimmers returning to Bondi Beach. The incident was filmed by a drone and made national news.
On 9 July 2013, surfer Bishan Rajapakse was knocked unconscious when a 15-metre humpback flicked him off his board with a swish of its tail, just 70 metres offshore. Fellow surfers transported the concussed rider in to the beach, who later joked, “maybe it was giving me a high five!”
Typically among the last southbound stragglers coming close to shore in October-November are the new-born calves on their first long-distance journey south, accompanied by their mothers. They usually swim closer to the shoreline to avoid hungry predators, especially orca, which roam in packs seeking vulnerable young whales on which to feed.
Orca - aka 'killer whale', although in fact it's not a whale but a large dolphin. Photo: Pixabay
Whales journeying south are more likely to engage in 'mugging' behaviour around boats, during which groups of them show curiosity in vessels they encounter, and close in to inspect them.
The word ‘cetacean’ is derived from the Ancient Greek ‘ketus’, meaning ‘monster-sized fish’, although they are not fish but warm-blooded mammals that give birth to live young, breathing air through a nostril ‘blowhole’, not filtered through gills.
There are 86 species of whales, dolphins and porpoises worldwide - all marine-dwelling carnivores with diets that range from miniscule plankton to fish to other whales.
45 species of cetacean are found in Australian waters, including 10 large whales, 20 smaller whales, 14 dolphins and a single breed of porpoise. Some of them are seasonal, others resident all year round.
Cetaceans can be divided into two categories of feeders:
Baleen, which have thin, frayed-end strainers for teeth through which they filter small marine creatures like plankton and fish.
Toothed, which generally prey on fish and squid, although some, like orca (aka “killer whales”, which are actually large dolphins and not whales, despite their name), also hunt seals or other cetaceans.
Humpbacks and Bryde’s whales engage in ‘bubble net’ feeding, an intelligent hunting tactic requiring group cooperation and coordination. After surrounding a school of fish, one whale dives beneath the shoal, then exhales carbon dioxide from its blowhole. This has the effect of enshrouding the fish in clusters of spiralling bubbles, disorienting them.
Then, another whale emits a loud noise beneath the confused fish, which panics them into swimming upwards in fright. The cluster of whales then forms a tight circle and follows their prey upward, their mouths agape to swallow the doomed fish at the ocean surface.
Grey Whale - Photo by Andre Estevez - Pexels
Humpbacks have been recorded remaining underwater for up to an hour. Orcas seldom remain underwater longer than 15 minutes and when hunting need to breathe frequently.
Whales and dolphins can’t breathe while they’re asleep, but they’re adept at snoozing parts of their brain while an active part enables them to stay afloat, breathe and watch for predators.
On 23 September 2020, the Journal of Experimental Biology reported that a Cuvier’s beaked whale, which not only holds the record for the deepest dive by a marine mammal (3000 metres), broke the previous 2014 record by another Cuvier’s whale for longest dive.
It stayed submerged for 222 minutes (3 hours, 42 minutes) before resurfacing for air.
Difference between dolphins and porpoises
Although dolphins and porpoises both navigate underwater via sonar from the ‘melon’ in their foreheads, they have significantly different faces, figures and fins.
Porpoises have rounder faces, smaller mouths and spade-shaped teeth whereas dolphins have elongated ‘beaks’ with cone-shaped teeth.
Porpoises are portly but dolphins are more streamlined. Porpoises have a triangular dorsal fin, like a shark, whilst dolphins’ fins curve.
However, dolphins often attack and kill porpoises in competition for food and territory.
Dolphin - Photo: Magda Ehlers / Pexels
Dolphins communicate via complicated whistling sounds through their blowholes, but scientists believe porpoises are incapable of making these noises due to the different shape of their blowholes.
There are 37 dolphin species worldwide (including five freshwater breeds of river dolphins) yet only six types of porpoises.
The single porpoise species in Australian waters - spectacled - inhabits cooler waters south of Tasmania and is not seen along the east coast of mainland Australia.
Dolphins are among the most intelligent creatures on the planet, and can learn and memorise complicated tasks as well as plan ahead. They’re sentient enough to recognise themselves in mirrors, feel empathy and display complex emotions like grief and elation.
They also communicate in their own complex ‘language’ which they utilise for hunting, defence and raising their young, as well as amusing themselves in surfing spectacles, sometimes performed in synchronicity.
Whale Tail - Photo: Francesco Ungaro / Pexels
Where to watch whales?
There are several high vantage points along the Sydney coastline from which to view whales, including: Ben Buckler Point, north of Bondi Beach; Burrows Park, Clovelly; and The Gap at South Head.
Further south, Magic Point, Malabar, and Solander Point at Kurnell are popular whale-watching spots.
On the Northern Beaches the new Burragula and Yiningma lookouts on North Head offer spectacular sea views, or Long Reef Headland and Barrenjoey Lighthouse.
Baleen whales sighted off the coast of Sydney include: Bryde’s, fin, humpback, minke (Antarctic and its dwarf subspecies), right (both southern and pygmy) and sei whales. Blue whales too, albeit once in a blue moon.
Toothed whales witnessed offshore include: southern bottlenose, pilot (long and short-finned), melon-headed, sperm (including pygmy and dwarf sub-species), and several ‘beaked’ species (Andrew’s, Arnoux’s, Blainville’s, Cuvier’s, ginkgo-toothed, grey, Shepherd’s and strap-toothed).
Several species of dolphins inhabit the coastal waters around Sydney, including bottlenose, common, dusky, hump-backed, Indo-Pacific, pantropical, Risso’s, rough-toothed, spinner (which perform spectacular, corkscrew-like acrobatic flips), striped, and the orcas (including false killer whales and pygmies). Some dolphins swim into bays to feed or even surf the waves breaking close to shore!