Story: Natural environment
Page 2 – Coasts
All roads lead to the coast. There is no location in New Zealand that is more than 130 km from the sea. It is a very long coastline: estimates range from 15,000 to 18,000 km. The exact length is obscured by the countless twists and turns around inlets, headlands, spits, bays, harbours, fiords, sounds and estuaries. Although the North Island is smaller than the South Island, it has a longer coastline.
About two-thirds of New Zealand’s coastline is hard rocky shore, while soft shores of sand or gravel cover the remainder. Some 80% of it is directly exposed to the sea, with the rest sheltered in harbours and estuaries. The west and southern coasts are more exposed.
Warm, salty, sub-tropical currents bathe the north and west of the country, while cold, less saline, subantarctic currents wash up from the south. Summer water temperatures on the continental shelf range from about 21°C in the north to 14°C in the south. Swimming at northern beaches is much more common than on southern shores.
New Zealand’s coastal waters support hundreds of fish species and many marine invertebrates. Fur seals, sea lions, dolphins and whales also frequent these waters.
Who’s eating who?
Shark attacks in New Zealand waters are rare. The many shark species that cruise coastal waters have long had more to fear from humans – much of the ‘fish’ in the popular fish and chips is actually shark. It was a favourite part of the Māori diet, and dried shark eggs were a particular delicacy. In the 1850s on Rangaunu Harbour, Northland, the Te Rarawa people caught 7,000 schooling sharks during two hunts.
Coastal waters have many kelp-covered reefs that attract fish and other life. Summer water temperatures vary from 9°C at Campbell Island to 24°C at the Kermadecs. Consequently there is considerable variation in fish species and other marine life. Some species such as snapper and kingfish are distinctly northern, while others such as girdled wrasse, telescope fish and sea perch are characteristic of the south.
The estuaries and coastal waters abound in shellfish. Mussels, pāua (abalone), pipi and many other shellfish form an important part of the Māori diet – kai moana (food from the sea). Pāua and scallop shells are often used as decoration in gardens or holiday homes.
Penguins – the birds that want to be fish – abound in New Zealand’s waters. The most common is the little blue penguin or korara, found from Northland to Stewart Island. With slate-blue plumage and a bright white belly the little blues are the world’s smallest penguins, just under 25 cm tall, and weighing a little over 1 kg. They breed underground in burrows or natural hollows. In coastal towns such as Ōamaru in North Otago, Oban on Stewart Island, and even in the capital Wellington, their nests are sometimes found under houses.
The deep waters beyond the continental shelf are not well understood. Huge areas of deep water, much of it barren of fish, extend over a muddy seafloor. These are underwater deserts. But even in the deep oceans there are oases – in the form of higher land known as seamounts or rises. Marine life flourishes on and around these subterranean mountain ranges and peaks, which occasionally rear up from the muddy plains. They are rich fishing grounds and a haven for marine life.