Whales belong to a group of mammals called cetaceans, which also includes dolphins and porpoises. Most people call the larger cetaceans whales, and the smaller ones dolphins. However, some species that we call whales actually belong to the dolphin family. In New Zealand there are five such whales: the killer whale (orca), short-finned pilot, long-finned pilot, false killer and melon-headed whales.
Almost half the world’s approximately 80 species of cetaceans are found in New Zealand’s waters. This is not surprising as New Zealand controls the fourth largest marine territory in the world, its waters are rich with foods that these mammals need, and it is on the migratory path of the largest whales.
Of the 38 cetaceans known to inhabit New Zealand waters, 22 are whales, but only a half dozen are relatively common. Some species, such as sperm whales, are highly visible and attract thousands of tourists to towns like Kaikōura. Others, such as beaked whales, are rarely seen and are known only because they beach themselves when injured or ill.
All whales are long and streamlined. They lack external hind limbs but have powerful tails that provide propulsion. Often they lift their tails above the surface before diving – an action known as fluking.
Whales also have a layer of fat under the skin known as blubber, which can be up to 50 centimetres thick. Blubber stores energy and insulates the whale from the cold in deep water. It is thought that whales live for 30 to 80 years.
Whales evolved from land-based mammals. At some point they became aquatic, but like all mammals they still breathe air, give birth to live young and feed their calves with milk. New Zealand has a fossil record of early baleen whales going back 35 million years, and early examples have been found in the Waitaki Valley, north Otago.
There are two types of whale: baleen and toothed.
Baleen whales have long bristle-fringed plates, known as baleen, which are made of keratin (a protein also found in human hair and fingernails) and fixed to the roof of the mouth. These sieve the minute crustaceans, such as krill, that they feed on. Baleen whales have two blowholes. And unlike some other whales, they do not use echolocation (emitting sounds to locate solid objects).
Baleen whales include the largest animals ever known. Greatest of all is the blue whale; the heaviest ever recorded was a female of 190 tonnes. Baleen whales migrate through New Zealand waters on their way south to feed on krill, which are abundant in the Southern Ocean. Of the world’s 13 species of baleen whales, eight are known in New Zealand, but only two, the southern right whale and Bryde’s whale, breed in New Zealand waters.
Toothed whales have teeth, rather than baleen, and a single blowhole. They find their prey through echolocation, emitting a series of clicks that travel through the water until they meet an object and are reflected back. By using a range of frequencies the whale can make a detailed examination of the object. Some scientists have suggested that the clicks may stun the prey. Toothed whales include sperm whales, which are relatively common around New Zealand, and the much rarer beaked whales, which have a small head with a beak and a bulging forehead.
The blue whale (Balaenoptera musculus) is the largest animal ever to live. On average, adults weigh between 100 and 120 tonnes, and males are 23 metres long, while females are 24 metres. The whale’s heart weighs 2 tonnes and pumps about 270 litres with each beat. A child could fit inside the aorta (the blood vessel leaving the heart), and the main arteries are the diameter of sewer pipes. Even when the blue whale is under the greatest strain, its heart rate is no more than 20 beats a minute – compared with a human rate of 60–80.
In naming the blue whale, the 18th-century Swedish naturalist Linnaeus used the Latin word ‘musculus’ which means ‘a little mouse’. In giving this name to the largest animal in the world he may have been playing a joke. However, ‘musculus’ can also mean ‘muscle’ – perhaps a bit more appropriate.
On a diet of over 200 litres of milk a day, a whale calf puts on 90 kilograms daily, and by weaning time eight months after birth, it can weigh more than 20 tonnes. An adult was once found to have 1 tonne of food, mainly krill, in its stomach.
Blue whales are a mottled blue-grey and acquire a yellowish sheen from algae on their skins, explaining their common name ‘sulfur-bottoms’. Their tiny dorsal fin is set far back on the body. They have the loudest voice underwater of all animals, and their low frequency sounds travel hundreds of kilometres.
When a blue whale was washed ashore near Ōkārito in 1908, the naturalist Edgar Stead and some friends retrieved the bones for the Canterbury Museum. Beset by sandflies, screeching gulls and the stench of rotting flesh, they attacked the whale carcass with knives, slashers, axes, shovels and a saw. The bones were then shipped to Lyttelton, and the public first viewed the 9-tonne skeleton in March 1909.
Blue whales were plentiful until the end of the 19th century because their speed (30 kilometres per hour) gave them the edge on non-motorised chaser boats. Hunted relentlessly in the 20th century, their numbers have plummeted. There are estimated to be fewer than 2,000 in the southern hemisphere. On their migration between the summer feeding grounds in the Antarctic and the equatorial waters where they spend the winter, blue whales used to swim through Cook Strait, and during the 19th and 20th centuries Tory Channel whalers would sometimes kill one. Blue whales still migrate past the New Zealand coasts, but are rarely seen close to shore.
Fin whales (Balaenoptera physalus), named for their prominent dorsal fin, are rare in New Zealand waters. The second longest of the whales at an average 20 metres, the fin whale has an asymmetrical colour scheme as its right jaw, but not its left, is white. It is believed that they live up to 80 years.
The fin whale produces the lowest frequency sound in nature – below the range of human hearing – but it can be heard by other fin whales thousands of kilometres away. In the 1960s, when United States navy personnel first heard the whales’ deep moans, they could not believe they were animal sounds.
The fin whale is also remarkable for its long migration, and its speed. It travels as far as 20,000 kilometres each year from the Antarctic to the tropics to mate and calve. Known as the ‘greyhound of the oceans’, it is noted for its stamina. One whale averaged 17 kilometres per hour over 3,700 kilometres.
The southern hemisphere population is estimated to be about 20,000, a fraction of the pre-whaling numbers. From the 1950s to the 1970s Soviet whalers killed 720,000 in the Southern Ocean region.
The southern right whale (Eubalaena australis) is the baleen whale most closely associated with New Zealand because it used to come inshore to sheltered harbours to mate and calve. Other species of baleen whales were usually seen further out to sea as they migrated between their Antarctic feeding grounds and breeding grounds in warmer latitudes.
Southern right whales used to occur as far north as the Kermadec Islands, along New Zealand’s coasts, and as far south as the subantarctic Auckland Islands and Campbell Island. Today they are rarely sighted around the mainland.
In the 1840s there were so many right whales in Wellington Harbour in the winter that some settlers complained the whales’ blowing kept them awake at night.
The storm-tossed Auckland Islands and Campbell Island, respectively 500 and 700 kilometres south of New Zealand, are the strongholds of the southern right whale. Every winter the whales come to give birth and mate there. Since the Second World War, when coast watchers were stationed on Campbell Island, reports of small numbers of right whales have been common. Although there are more whales at the Auckland Islands, the first inkling of a sizeable population only came in the early 1980s when a yachtsman spotted at least 75 there.
Where the whales go from October to May is a mystery. It is believed they head for rich feeding grounds – most likely in the Southern Ocean – to build up their reserves for the winter, when feeding is less of a priority.
The right whale is a large, stocky, black whale, 15–18 metres long with broad flippers. Its lack of a dorsal fin makes it easy to identify. The arched upper jaw is covered in callosities – crusty outgrowths of skin which are often made white by infestations of whale lice. It also has a unique blow, with the water rising in two columns to form a ‘V’ 5 metres high.
Right whales were the most vulnerable of all the baleen whales: slow-paced swimmers (travelling no more than 9 kilometres per hour), they were easy to catch; they supplied larger quantities of oil than other species; when harpooned they floated rather than sank; and their baleen (‘whalebone’) was valuable as it is fine and flexible and was used for a range of items such as corsets, umbrella ribs and riding crops. For all these reasons, early whalers described the species as ‘the right whale’.
Hunting decimated their numbers – only the blue whale suffered a greater population decline.
Before whaling there were estimated to be 10,000 in the whole New Zealand region. In the 2000s there were probably about 250 (mostly around the Auckland and Campbell islands). But around New Zealand’s mainland the few sightings made since the late 1990s suggest that there are fewer than 30 right whales in the population. The low numbers persist despite protection since 1935, perhaps because females only calve every three years.
The humpback’s scientific name is Megaptera novaeangliae. Megaptera means ‘big wing’. This refers to its flippers, the largest appendages of any animal – up to 5 metres long and about a third of its length. The name ‘humpback’ came from whalers who noticed that, just before diving, this whale arched its back more than others, exaggerating the hump around its dorsal fin.
Humpbacks are black with variable white markings on the underside of the tail fluke. These markings, like flaking white paint, are unique to each whale. The large flippers are usually white. The head is knobbly with protuberances, and the whale’s jaw and throat grooves are often encrusted with barnacles.
Humpbacks have developed a technique known as bubble netting to catch fish. They swim beneath a school of fish and, spiralling round, release a string of bubbles from their blowhole. These form a net around the fish, and the whales then rise through the centre to surface, open-mouthed, catching their feast.
Humpbacks do a good deal of acrobatic clowning – flipper slapping and leaping out of the water to splash down on their backs. The males also produce the longest and most varied songs in the animal world – a complex sequence of whistles, rumbles, groans, moans and clicks, which can last for 20 minutes and be repeated over and over.
Humpbacks are occasionally seen off the New Zealand coast, swimming between the Antarctic, where they spend the summer feeding on krill, and the tropics, especially Tonga, where they breed in winter. They often used to travel north along the east coast of New Zealand and back southwards down the west coast, sometimes passing through Cook Strait.
In the early 1890s the Cook family of Whangamumu, Northland, noticed that humpback whales used to pass between a low-lying rock and cliffs near Cape Brett. They slung steel mesh nets between the island and the shore, and the whales became hopelessly entangled in the mesh, presenting an easy target for chasing boats.
In the 20th century whalers caught over 200,000 humpbacks in the southern hemisphere. Illegal Soviet whaling from the 1950s to 1970s contributed a quarter of that number. Between 1911 and 1964 New Zealand whalers, most of them based around Cook Strait, killed over 5,000 humpbacks.
Since the end of humpback whaling the numbers have only slowly increased, despite big increases in Australian waters. However, in 2015 during the Department of Conservation's annual four-week Cook Strait whale survey, 137 humpback whales were counted. This compared with 40 in 2008.
Capable of outrunning sail and rowboats, the sei whale (Balaenoptera borealis) was protected from whaling by its remarkable speed – until the advent of motorised chasers. The sei has been recorded at 50 kilometres per hour in a sprint. One travelled 4,320 kilometres in 10 days, indicating an average speed of 16 kilometres per hour if it made the trip without a rest.
Medium sized for a baleen whale, at an average weight of 20–25 tonnes and a length of 15–18 metres, the sei is nevertheless the equivalent of four large elephants. It is lean and sleek, steely grey, and has a high dorsal fin. It is estimated to live for more than 50 years.
Sei whales use two feeding methods. With their mouths half open they skim the sea’s surface for prey, then swallow what has collected on their 300–400 baleen plates. Alternatively, they open their mouths wide, taking in a huge quantity of food and water, then expel the water to leave the food behind.
Around February and March sei whales migrate south to Antarctic feeding grounds, but do not venture near the pack ice, as blue or fin whales do. They return to warmer waters to calve, passing through the Pacific Ocean to the east of New Zealand between the mainland and the Chatham Islands. The International Whaling Commission, which monitors whale populations, has no estimate for sei whale numbers.
Sometimes described as the ‘tropical’ whale, Bryde’s whales (Balaenoptera edeni) prefer waters warmer than 20°C, which are generally found in northern New Zealand.
The correct pronunciation of Bryde’s is ‘brewdus’. This whale is named after Johan Bryde, the Norwegian consul to South Africa, who built the first whaling stations in Durban.
It is the most common of the baleen whales around the New Zealand coast, and is seen mainly in springtime in the Bay of Plenty, Hauraki Gulf and off the east coast of Northland. Whether it migrates long distances is uncertain. Some experts believe Bryde’s whales, seen off the coast, mate and calve locally.
From a distance the Bryde’s whale is often confused with the sei: they are both sleek and grey, with a pointed dorsal fin. The Bryde’s is the second smallest of New Zealand’s baleen whales (the minke being the smallest), with an average weight between 16 and 20 tonnes and a length of 12–15 metres. Unlike many other baleen whales, which eat krill in polar waters, the Bryde’s feeds on fish, such as pilchards, mackerel and mullet.
The Bryde’s has been spared large-scale whaling. Up until 1962, New Zealand whalers working at the Whangaparapara station on Great Barrier Island hunted Bryde’s whales, although only 17 were ever taken. Out of an estimated original population of 60,000, there may be 40,000 left.
The minke whale is now believed to consist of two species:
In New Zealand minke whales are not commonly seen, although of all the baleen whales they are the most likely to become stranded on the coast.
The dwarf minke, which is most often seen, is about 7 metres long, while the southern is about 9 metres long. The minke is also called the ‘piked whale’ or ‘sharp-headed finner’, because of its sharply pointed head. It is chunkier than its relatives and has a dark grey back with variable whitish markings. Sometimes there is a distinctive white band on the flipper.
Like the blue whale, the minke favours cold waters close to the Antarctic ice where it feeds on krill, but around New Zealand it relies more on fish and squid.
Whalers did not bother with minkes until the latter half of the 20th century, when the larger whale species had been hunted out. Since 1987 the Japanese have been killing more than 300 minkes a year, in defiance of world opinion, for purposes they define as scientific research.
There is debate about the size of the world’s minke population, but it is likely to be between 500,000 and 1,000,000.
The sperm whale (Physeter macrocephalus) is often pictured in 19th-century images of whaling, and was made famous by Herman Melville in his novel Moby Dick. In terms of survival, this species is one of the more successful: it has survived for millions of years and remains one of the most numerous of the large whales, despite centuries of hunting.
The sperm whale has a huge square head, with a small underslung jaw. Its skin is dark grey to dark brown and corrugated. In place of a dorsal fin, it has a hump and a series of knuckles. It has triangular flukes which it raises before diving. The blowhole is off to the left and when the whale blows, the blast shoots forward at a 45º angle.
The sperm whale was named by the early whalers who discovered whitish oil in the whale’s head and thought the fluid looked like semen. It is possible that this spermaceti oil helps to focus the sound emitted during echolocation, and to stun the whale’s prey.
The sperm whale is by far the largest of the toothed whales, and the size difference between males and females is much more marked than in any other whale species. Males are about 18 metres long and weigh 32–45 tonnes, and are up to 40% longer and 300% heavier than females. The sperm whale’s brain weighs almost 10 kilograms, and is the heaviest of any animal.
Sperm whales are found at Kaikōura in the South Island, to the west of Stewart Island, off East Cape and North Cape, and in pockets to the west of New Zealand. In the 19th century the major hunting grounds were north-east of New Zealand near the Kermadec Islands.
The sperm whale captures its prey by diving deep into the ocean’s trenches. It reaches depths of 3,000 metres, descending at a rate of over 100 metres a minute. The whale can stay there up to an hour and, in the dark, find its prey by echolocation. On surfacing, the whale takes 45–50 breaths to re-oxygenate.
The social behaviour of sperm whales is unusual. Females and males live mostly separate lives. Small groups of up to 50 closely related whales, usually consisting of several females and immature whales of both sexes, live together for up to 10 years. Their need for cooperation is vital: when a cow spends an hour away on a deep fishing expedition, her vulnerable calf requires babysitting. Young males leave the whale nursery school at between 7 and 10 years of age to form bachelor schools before starting to breed at about 25. As adults, the males become increasingly solitary and begin to feed in Antarctic waters.
Herman Melville gave this title to one chapter of Moby Dick. He explained that a school of female sperm whales was usually accompanied by one male, who would swim at its rear and was known by the whalers as the ‘schoolmaster’.
Kaikōura, on the east coast of the South Island, is the only place in the world with a deep-water canyon close to shore that attracts sperm whales. Just 4.5 kilometres from shore, the continental shelf suddenly falls away and the ocean plunges 1,000 metres. Here the whales dive for the famed giant squid, as well as groper and ling.
Kaikōura is a foraging ground for about 80 bachelor whales. About half of those that have been identified remain at Kaikōura for more than one season. The others move on. These are probably older males, passing through on their way to Antarctic waters, or expelled by the younger whales.
While Kaikōura sperm whales eat squid, fish also make up a significant proportion of their diet. Studies in the 1960s of sperm whales killed in the Cook Strait region showed that squid accounted for 65% of their food, and groper and ling the remaining 35%. Depending on their size, sperm whales eat anywhere between 400 and 1,000 kilograms of food a day, or 3% of their body weight.
The pygmy sperm (Kogia breviceps) is a small grey whale up to 4 metres long, which is more often seen after stranding than at sea. It too has spermaceti oil in its head. The pygmy is hard to distinguish from the very much rarer dwarf sperm whale (Kogia simus).
The chance of seeing any of the 11 species of beaked whales known to inhabit New Zealand waters is slight. In some cases the only proof of their existence is their bodies washed up along the coastline.
These enigmatic creatures are the least known marine mammals. Their ancestors first appeared about 25 million years ago, making beaked whales one of the earliest whale groups to evolve. Worldwide there are 21 species, and fresh discoveries continue to be made. For example, a pygmy beaked whale, believed to exist only off South America, was found stranded near Kaikōura in 1991.
Beaked whales live in the open ocean, diving at least 300 metres for squid. Varying in length from about 3 metres to 13 metres, they have a small head, a beak and bulging forehead, and pockets for their flippers. The males of some species have teeth that emerge from the bottom jaw like tusks, which they may use to fight other males for females – they have ample scratches to support the theory. However, no one has ever witnessed such battles.
New Zealand’s national museum, Te Papa Tongarewa, has the world’s largest collection of beaked whale skeletons. In the absence of any work on the behaviour of live animals, research in New Zealand concentrates on stranded whales.
The stranding of a Shepherd’s beaked whale (Tasmacetus shepherdi), also known as the Tasman beaked whale, allowed researchers to see exactly what the whale looked like. Up until then, the colour pattern had been determined largely by guesswork. This beaked whale was first discovered and named in 1933 by George Shepherd, curator of the Wanganui Museum, who collected a specimen along the Whanganui coast that year. The skeleton is held at the museum.
Little is known about beaked whales’ vocal signals. In 1995 researchers, including Otago University’s Steve Dawson, first recorded signals from a species known as Baird’s beaked whale off the North American west coast. Instead of clicks made in sequences, with the click rate changing gradually (as for sperm whales and dolphins), Baird’s whales produce an irregular series of few clicks. Some beaked whales also whistle, while others, such as Cuvier’s, appear to make no signal at all.
The beaked whale that becomes stranded most often in New Zealand waters is the Gray’s beaked whale (Mesoplodon grayi), also known as the scamperdown whale. It is therefore assumed to be the most common beaked whale in the region. These whales form small herds, and in the 19th century there was a mass stranding of 25 in the Chatham Islands. This implies a similarity with social species such as pilot whales, which sometimes become stranded in large groups.
The male strap-toothed beaked whale has teeth that wrap around its jaw so that it can barely open its mouth. So how does it feed? And how do females, which have no teeth, grasp their prey? Scientists believe the whale sucks up its prey – squid from deep offshore canyons. That belief is backed up by observations of a captive Hubb’s beaked whale, which, when offered some squid, instantly slurped it up.
Three other beaked whales found occasionally in New Zealand are Arnoux’s, Cuvier’s, and the strap-toothed beaked whale. Each has different tooth formations. Arnoux’s beaked whale, or the Southern four-tooth whale (Berardius arnouxi), has two pairs of teeth, one at the front of the jaw and one further back. Cuvier’s beaked whale, or the goose-beaked whale (Ziphius cavirostris), has a single pair of teeth at the very tip of the jaw. The strap-toothed beaked whale (Mesoplodon layardii) has a pair of tusks.
Other beaked whales which have been found rarely in New Zealand waters are the southern bottlenose whale (Hyperoodon planifrons), Andrew's beaked whale or splay-toothed whale (Mesoplodon bowdoini), the dense-beaked whale (Mesoplodon densirostris), the gingko-toothed whale (Mesoplodon gingkodens), Hector’s beaked whale (Mesoplodon hectori), and the Peruvian beaked whale (Mesoplodon peruvianus).
New Zealand is one of the main locations for whale and dolphin (cetacean) strandings. Records of strandings have been kept since 1840. Even though early records are sketchy and were usually of strandings near centres of population, they do show trends. About 13,000 individual cetacean strandings have been recorded, and by 2006 over 2,000 creatures had been successfully rescued.
Certain areas are stranding hotspots: Ōpoutama (Māhia Peninsula), Golden Bay and the Chatham Islands. Some species are attracted to particular areas: sperm whales to Kaipara Harbour and pilot whales (which belong to the dolphin family) to Doubtless Bay, Ninety Mile Beach and Stewart Island. In 1998 Doughboy Bay, western Stewart Island, was the scene of 328 pilot whales stranding.
Just six species account for 88% of strandings: the long-finned pilot, sperm, false killer, pygmy sperm, Gray’s beaked whales and the common dolphin. Three of these species, the long-finned pilot, false killer and the sperm whale, are mass stranders. In 207 incidents, more than 9,000 long-finned pilot whales have beached themselves, with just over 2,000 being successfully refloated. In 1918, New Zealand’s (and the world’s) worst recorded stranding occurred when around 1,000 pilot whales came ashore at Long Beach, Chatham Islands.
Pilot whales are members of the same family as dolphins. The long-finned whale (Globicephala melaena) is larger than the short-finned (Globicephala macrorhynchus), and more common around New Zealand. Both frequent deep water, which accounts for the difficulties they experience when they encounter unfamiliar shallow waters.
Scientists believe there are three main reasons why New Zealand’s coastline is such a hazard for cetaceans:
There are other possible causes:
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