Whales and Dolphins

Whales and Dolphins – Visitors to the Taputeranga Marine Reserve 

None of the marine mammals that frequent the Cook Strait region are ‘resident’ in the marine reserve. They are all wide ranging species with breeding places often many hundreds of kilometres away. Fur seals (see separate article) forage around the reserve but commonly only haul out locally at Red Rocks beyond Palmer Head.

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 Pod of dolphins Photo: Jim Mikoz

Whales and Dolphins 

Strictly speaking all Cetaceans are whales, including dolphins and porpoises. The main division for whales is whether they are toothed (Odontoceti) or whether the sieve their food, such as krill, through baleen plates in the mouth (Mysticeti). Dolphins are small whales, belonging to the Family Delphinidae, and are considered distinct from porpoises (Family Phocoenidae). In New Zealand waters we mainly need only to consider large whales and smaller dolphins. The only known porpoise in these waters is the spectacled porpoise, regarded as a rare critter in this part of the world. Dolphins are amongst the fastest swimmers in the sea, reaching speeds of 20 knots at times, easily able to ride the bow wave of ships and sustain the speed effortlessly. 

Of the larger whales, humpback, southern right and sperm whales have been seen in Cook Strait in small numbers, and more rarely an occasional fin whale. Blue whales used to travel through Cook Strait, but now remain well offshore. Dolphins are considerably more often seen than the larger whales, notably common dolphin, orca (the ‘killer whale’ is a member of the dolphin family), bottlenose and sometimes dusky. Much less common are Hector’s dolphin, perhaps because they are critically endangered and few in number. The renowned Pelorus Jack was a Risso’s dolphin, which met ships passing Pelorus Sound and Admiralty Bay, in the Marlborough Sounds from 1888 to 1912. Very few of this species are seen in South Pacific waters. 

Humpback 

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Humpback whale tale slapping  Photo: DOC

Humpbacks may be seen annually passing through Cook Strait from Antarctic feeding grounds to the warmer waters off Tonga for breeding in winter months. They arch steeply before diving, giving the back a humped appearance.  Many humpbacks were killed in southern waters during the early 20th century and they are just now making a slow comeback in numbers. They are black with large, white flippers, white under tail and their heads are often barnacle covered. They are known for slapping the water with their flippers, jumping out of the water to splash down (possibly to dislodge parasites, or for the sheer pleasure of it). They are also renowned for ‘bubble netting’ – blowing bubbles to channel fish together in a column, then rising up through the middle with mouth wide open! In recent years they have been subject to a census as they travelled through Cook Strait, with a record number of 106 whales seen in 2013. 

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Dead humpback, Pencarrow. Note baleen plates Photo: Phil Reid

Southern right whales

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Southern right whale, Wellington Harbour Photo: DOC

Named as the ‘right’ whales to catch, as they were slow to chase, floated after being harpooned and were the source of valuable oil and baleen plates which had a host of uses in the 1900’s. They were once frequent in coastal locations around New Zealand, coming into bays and inlets. Apparently Wellington Harbour in the 1840’s had so many right whales at times that people would complain about the blowing of the whales at night. They use the Auckland and Campbell Islands as a stronghold, frequenting the embayments there as a place to give birth in winter. The rest of the year is a bit of a mystery, though they must feed in the rich krill grounds of the Southern Ocean over summer. One whale visited Wellington Harbour in 2011. 

Sperm whales 

Sperm whales have a very square head and small jaw and are the largest of the toothed whales. They are a tourist attraction off Kaikoura, where they dive to great depths (to over 1000 m) to feed on giant squid and ling. The population at Kaikoura is entirely of young males. They will have come initially from a social group, sharing in looking after very young calves while mothers are away diving deep for food. As they age, the juveniles are driven off to live at feeding grounds like Kaikoura. Later still, adult males live a more solitary life, though in ‘Moby Dick’ Melville write about males ‘riding herd’ on groups of females. The species ranges between Antarctic waters and the Kermadecs. 

Common dolphins

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Common dolphin Photo: Jesus Renedo, OCEANA

These may be seen in schools of up to several hundred individuals, making long arching leaps. They often approach boats to ride the bow wave. Common dolphins frequently leap and do spectacular spins in the air. The species is known from its prominent ‘beak’, high dorsal fin, a crisscross pattern of colours from purplish-black, dark grey, white and creamy tan and it has a low, smoothly sloping head. Large specimens grow to just over 2 m in length. 

http://www.stuff.co.nz/dominion-post/news/eastern-suburbs/6677907/Dolphins-spotted-off-Wellingtons-south-coast 

http://www.youtube.com/watch?v=CnKQmh8-lGU 

Bottlenose dolphins

Bottlenose dolphins are among the largest of dolphins, their stout torpedo-shaped body growing up to 3.1metres long. They are widely distributed throughout the world’s seas. They are usually dark grey on the back, fading down to white or pink on the belly and have a distinct short beak, long pointed flippers and a sickle-shaped dorsal fin. Bottlenose dolphins frequently leap out of the water in displays of much spinning and splashing. They will also ride the surf of a ship’s bow and slap the water with their fin or head. These actions may be a source of entertainment to the dolphins, but are also likely to serve as practise for more important functions such as communication, food-herding and predator defence. They are susceptible to predation by sharks and orca, and individuals suffer from boat-strike. 

http://www.stuff.co.nz/dominion-post/capital-life/8368466/The-day-the-dolphins-came 

Orca 

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Orca in marine reserve Photo: Steve Meads

An estimated 150 to 200 orca inhabit New Zealand waters. They travel long distances between locations, sometimes coming right into harbours. They are sometimes seen doing tail stands, breaching and slapping their flippers on the water. These animals grow to around 9 m. They are easily recognised as they have black backs and white underside, sharply differentiated, with white patches behind the jawline above the eye. Males have tall triangular fins and they are the largest of the dolphins, at 8 – 9 m and up to 5 tonnes in weight. They are known as ‘whale killers’ as they have a fierce reputation as predators, attacking larger whales. They are not known for killing humans, other than at sea aquaria in captivity. They are frequent visitors to the Wellington South Coast, often entering Wellington Harbour. 

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Orca with VUW researchers Photo: P Mensink

Whales and dolphins have earned much greater respect and interest in recent times, as more knowledge and understanding of their nature, socialisation, vocal communications and high level of intelligence have been gained. They are still harvested for reasons that seem to be traditional or cultural rather than real need for human consumption, often with extremes of cruelty and barbarity in methods of killing. Just as much, dolphins and orca have been captured and trained like circus animals to entertain. Equally, now, there is strong advocacy for their protection in their natural habitats (all marine mammals are fully protected in New Zealand seas) and for appreciation of their intelligence. They seem very much free spirits of the sea, genuinely enjoying their abilities to swim, leap and play. 

New Zealand diver, explorer and marine biologist, Wade Doak, has spent a lifetime living with dolphins, both in local seas and throughout the Pacific, recording much of indigenous people’s interactions with dolphins (and sharks). He has worked to establish communications with dolphins and to record their reactions to mimicry of their whistling and communications amongst themselves. His results serve to add more to an appreciation of high intelligence in dolphins and a reminder that in the marine environment, the human species is limited and is the lesser being. There are even moves now to give international legal recognition to dolphins and perhaps other animals as possessing intelligence, though yet poorly understood, and thus having rights to exist and have respect. 

Sources: 
‘Whales and Dolphins of New Zealand and Australia: An Identification Guide’ Alan N Baker, Victoria University Press, 1983. 
Te Ara Encyclopaedia of New Zealand 
‘Gaia Calls’ Wade Doak, Divine Arts Media, 2012