Жаңа Зеландиядағы Кайпара шығанағы

Harbour estuary in New Zealand

Kaipara Harbour is a large enclosed harbour estuary complex on the north western side of the North Island of New Zealand. The northern part of the harbour is administered by the Kaipara District and the southern part is administered by the Auckland Council. The local Māori tribe is Ngāti Whātua. By area, the Kaipara Harbour is one of the largest harbours in the world. It covers at high tide, with exposed as mudflats and sandflats at low tide. According to Māori tradition, the name Kaipara had its origins back in the 15th century when the Arawa chief, Kahumatamomoe, travelled to the Kaipara to visit his nephew at Pouto. At a feast, he was so impressed with the cooked root of the para fern, that he gave the name Kai para to the district. Kaipara comes from the Māori kai meaning "food", and para meaning "king fern".

The harbour extends for some from north to south. Several large arms extend into the interior of the peninsula at the northeast of the harbour, one of them ending near the town of Maungaturoto, only ten kilometres (6 mi) from the Pacific Ocean coast. The harbour has extensive catchments feeding five rivers and over a hundred streams, and includes large estuaries formed by the Wairoa, Otamatea, Oruawharo, Tauhoa (Channel) and Kaipara. A number of small islands off the shoreline are connected to the mainland by mudflats at low tide. The Kaipara Harbour is broad and mostly shallow, as it is formed from a system of drowned river valleys. The harbour shoreline is convoluted by the entry of many rivers and streams, and is about long, being the drainage catchment for about 640,000 ha of land. and is over deep in parts. On average, Kaipara tides rise and fall Spring tidal flows reach 9 km/h (5 knots) in the entrance channel and move 1,990 million cubic metres per tidal movement or 7,960 million cubic metres daily. The harbour head is a hostile place. Big waves from the Tasman Sea break over large sandbanks about five metres below the surface, two to five kilometres from the shore. The sand in these sandbanks comes mainly from the Waikato River. Sand discharged from this river is transported northward by the prevailing coastal currents. Some of this sand is carried into the Kaipara harbour entrance, but mostly cycles out again and then continues moving northwards along the west coast. The southern sandbanks at the entrance are constantly accumulating and releasing this sand. For this reason, a lighthouse was built in 1884 on the northern arm of the entrance (Pouto Peninsula). It was automated in 1947 and closed in the mid 1950s. The structure still exists and was renovated in 1982–84. In Māori mythology, the ocean going canoe Māhuhu voyaged from Hawaiki to New Zealand and overturned on the northern side of the entrance. It was commanded by the chief Rongomai, who drowned. His body was eaten by araara (white trevally), and his descendants to this day will not eat that type of fish. The first European shipwreck was the Aurora, a 550 ton barque, in 1840, and the most recent was the yacht Aosky in 1994. Today, the remains of wrecks still become visible under certain tidal and sand conditions. The Kaipara is rarely used today for shipping, and no large settlements lie close to its shores, although many small communities lie along its coastline.

The Kaipara Harbour is a drowned river valley system, which first formed 2 3 million years ago as an open bay, becoming a sheltered harbour as elongated sand dune barriers formed at the harbour's mouth. Over the last two million years, the harbour has cycled between periods of being a forested river valley and a flooded harbour, depending on changes in the global sea level. The present harbour formed approximately 8,000 years ago, after the Last Glacial Maximum. The area includes 125 square kilometres of mangrove forest. with subtidal fringes of seagrass. The Kaipara is a migratory bird habitat of international significance. Forty–two coastal species are known, and up to 50,000 birds are common. Rare species use the harbour for feeding during summer before returning to the Northern Hemisphere to breed, such as the bar tailed godwit, lesser knot, and turnstone. Threatened or endangered native species, such as the North Island fernbird, fairy tern, crake, Australasian bittern, banded rail, grey‑faced petrels, banded and NZ dotterels, South Island pied oystercatcher, pied stilt, and wrybill are also present Significant local populations of black swan, pūkeko, and grey duck also breed in the area. The spit was an important habitat for the Caspian tern. The birds have moved to other parts of Kaipara Harbour, possibly due to human disturbance. An air weapons range used by the New Zealand Defence Force is a short distance south of the spit.

Māori settlements and marae have been scattered around the harbour margins for hundreds of years. The waterways of the Kaipara provided, and still provide, Māori with resources and a ready means of moving between marae.

In 1839, European settlers began arriving in the Kaipara to fell and mill kauri trees and build boats for local requirements. The first sailing ship wrecked at the entrance to the harbour was the Aurora in April 1840. The brigantine Sophia Pate was wrecked at South Head in August 1841 with the loss of all 21 on board. The Wairoa is the main river feeding the Kaipara from the north. Thirty kilometres upstream, the town of Dargaville was established. The stretch of water to Dargaville is broad and straight and provides an easy to navigate route into what were then kauri forests in the interior. Dargaville flourished and immigrants from Britain and Croatia were attracted to the area. Ships up to 3,000 tons carried timber and logs out along the Wairoa to defy the bar at the harbour entrance before continuing on, usually to another New Zealand port or across the Tasman to Australia. The Kaipara River is the principal river feeding Kaipara Harbour from the south. From 1863 Helensville established itself as a timber port on this river, and provided shipping services about the Kaipara. When the timber ran out, Helensville developed sheep and dairy farms, and more recently nut plantations, vineyards and deer farms. The Kaipara is the largest estuarine harbour on the west coast of New Zealand and provides significant areas of suitable breeding grounds and habitats for juvenile fish. It has fewer problems with water quality than the Manukau, and is the single most significant wetland for west coast fisheries. Early versions of oyster farming occurred between the early 1900s and 1950s. Thousands of tons of rocks were placed along the shorelines to act as an additional substrate on which the natural rock oyster could grow. In 2002, the Crown settled the historical claims of Te Uri o Hau, a hapu of the northern Kaipara Harbour. As part of the settlement, access to and the rights of the hapu to gather oysters within the existing "Maori Oyster Areas" were recognised. In 2008, resource consent was given to Biomarine to establish New Zealand's largest oyster farm in the Kaipara. The farm is projected to produce about NZ$30 million in annual exports and 100 new jobs. In recent years, there has been a perception amongst locals that commercial fishers have damaged fisheries in the Kaipara. Locals have been frustrated in their attempts to gain government support. The veteran filmmaker Barry Barclay has examined this in his 2005 documentary, The Kaipara affair.

Currently (2007) about 219,000 cubic metres of sand is mined each year from the entrance and tidal deltas of the Kaipara. This sand contributes over half the sand requirements for Auckland. The sand is used in the production of concrete and asphalt, and also in drainage systems and beach nourishment. A suction pump is usually used to extract the sand from the seabed. It is pumped into a barge as a sand and water slurry. As the barge loads, shells and other objects are screened out and the sea water drained back to the sea. The availability of sea sand within the Auckland region means the road costs of transporting sand from further parts of the country are avoided. Concerns about possible negative consequences of this sand mining have also been raised.

Management of the Kaipara Harbour does not have a central administration. Management is distributed among the Kaipara District Council, Auckland Council, Northland Regional Council, the Department of Conservation's Northland and Auckland section, and the Ministry of Fisheries. As part of the worldwide trend, there is a decline in biodiversity within the Kaipara. The timber industry removed most of the native forest. Much of the kauri and kahikatea forest, and scrub and riparian vegetation, has been replaced with farm and urban areas. Mangrove forests and wetlands have been "reclaimed". Soil erosion has increased on the land and sedimentation in the harbour. Shellfish abundance has declined, especially toheroa, scallops, tuatua, cockles and pipi. Finfish like mullet, snapper, kanae and school shark have diminished. Habitat fragmentation has also occurred. Natural vegetation in the Kaipara catchments have been reduced to islands of wetlands and forest in man made landscapes—separated by urban areas, roads, exotic forests and pastures. More information is needed on biodiversity in the Kaipara Harbour and habitats in associated coastal areas. A recent pilot survey found that habitats in the estuaries are still extensive, but ninety percent of land cover is no longer indigenous wetland or vegetation. Even if the key existing areas were to be protected, further buffers and corridors that give better connection between the natural areas would be needed to encourage the recovery of biodiversity.