Two extremely rare species – the New Zealand sea lion (Phocarctos hookeri a.k.a. Hooker’s sea lion) and Hector’s dolphin (Cephalarhynchus hectori) – are found only in New Zealand waters.
New Zealand sea lions mostly live around the sub-Antarctic Auckland Islands, 460km south of the South Island, but some breeding also takes place on the Otago Peninsula, along the Catlins Coast and around Stewart Island. The large, adult male sea lions are black to dark brown, have a mane over their shoulders, weigh up to 400kg and reach lengths of over 3m. Adult females are buff to silvery grey and much smaller – less than half the weight and just under 2m. Barracuda, red cod, octopus, skate and, in spring, paddle crabs make up their diet, with New Zealand sea lions usually diving 200m or less for four or five minutes – although they are capable of achieving depths of up to 500m. Pups are born on the beach, then moved by the mother at about six weeks to grassy swards, shrubland or forest, and suckled for up to a year.
Sea lions prefer to haul out on sandy beaches and in summer spend much of the day flicking sand over themselves to keep cool. Unlike seals they don’t fear people. If you encounter one on land, give it a wide berth of at least 10m (30m during the Dec–Feb breeding season), and if it rears up and roars, back off calmly but quickly – they can move fast.
The Hector’s dolphin, with its distinctive black and white markings, is the smallest dolphin in the world and, with a population around 7,000, is also one of the rarest. It’s only found in New Zealand inshore waters – mostly around the coast of the South Island – with eastern concentrations around Banks Peninsula, Te Waewae Bay and Porpoise Bay, plus western communities between Farewell Spit and Haast. They roam up to 8km from shore in winter but in summer prefer shallow waters within 1km of the coastline, catching mullet, arrowsquid, red cod, stargazers and crabs. Female dolphins are typically a little larger than the males, growing to 1.2–1.4m and weighing 40–50kg. They give birth from November to mid-February, and calves stay with their mothers for up to two years.
In summer and autumn, the tiny resident population at Porpoise Bay regularly enters the surf zone and even comes within 10m of the beach. Hector’s dolphins are shy and being disturbed can impact on feeding, which in turn affects their already low breeding rate. If you’re spending time around them, be sure to follow DOC rules (posted locally), which essentially forbid touching, feeding, surrounding and chasing dolphins and encourage you to keep a respectful distance. Swimming around pods with juveniles is also forbidden, and in summer most pods will have juveniles.