Mackenzie

The Mackenzie Basin/Te Manahuna

The Mackenzie Basin covers the catchment of the Waitaki River, the third largest catchment in New Zealand. The river catchment stretches from Lindis Pass in the south-west up past the northern edge of Mt Cook National Park (about the same latitude as Christchurch).

For many centuries the land that now forms the Mackenzie Basin was mostly covered in indigenous forest. However the arrival of Māori then Pākehā led to the gradual burn-off of the vegetation. The area was named after sheep rustler James Mackenzie, who in 1855 was thought to be the first European to have crossed Burke’s Pass. He grazed his stolen sheep on the by-then dry tussock landscape.

The Mackenzie, though, was well known to Māori and the Pass (then known as Te Kopi Opihi) was used as a route to the well-stocked inland Lakes Tekapo, Pukaki and Ohau, and its many rivers for gathering mahinga kai.

Further south runs the Waitaki River, the boundary between Canterbury and Otago, also known to Māori for rich sources of mahinga kai.

The geographic scope of the Mackenzie Basin Agency Alignment Programme

European settlement

In 1844, the first Europeans arrived in the Waitaki area, guided in from Moeraki through the Lindis Pass by local Māori. Although they did not stay, the visitors drew maps of the area which helped others find the way in.

By 1860, almost the whole Waitaki Valley was settled, with land allotted to European farming settlers on a first-come, first-served basis. High wool prices in Britain and the discovery of gold in the Maerewhenua River meant the new arrivals prospered.

Introduction of pests

Farmers replaced native grasslands with trees and pasture, and introduced a range of pests: gorse and broom, wilding conifers, lupins, cotoneaster, heiracium (hawkweed), rabbits and hares, feral cats, rats and stoats – all of them harmful to the local ecology and an impediment to grazing for sheep.

Demand for electricity generation led to construction of the 36 metre high Waitaki Dam, near Kurow, in the 1930s. A 25 megawatt power station at Tekapo was completed in 1951 and the big 110 metre high Benmore Dam was finished in 1965.

Three years later the Aviemore Dam completed the series of three dams and hydro lakes on the lower Waitaki River.

To accommodate the many dam workers, Twizel was established on what was to become the shores of Lake Ruataniwha. It is now a thriving holiday town, and the lake hosts major national rowing championships every year.

The steadily growing influx of tourists to and through the Mackenzie has created pressure on popular scenic areas around Pukaki, Tekapo and Aoraki Mt Cook village, and the growth of freedom camping in the area is threatening indigenous flora and fauna, particularly next to lakes and rivers.

Biodiversity - indigenous birds, fish, invertebrates and plants

Tenure review of pastoral land has delivered important gains for conservation. This has helped protect distinctive and rare ecosystems, and has led to the formation of high country parks, and improved public access and recreation.

There are more than 80 threatened or at-risk species among the unique biodiversity of the Mackenzie Basin, including several rare species of fish, invertebrates and birds.

Birds

The network of braided rivers, lakes, single channel rivers, wetlands and ponds provides crucial habitat for threatened bird species.

  • Kaki/black stilt (nationally critical)
  • Black-billed gulls (nationally critical)
  • Black-fronted terns (nationally endangered)
  • Wrybill (nationally vulnerable)
  • Banded dotterels (nationally vulnerable)
  • Terrestrial birds such as rock wren and kea (both nationally endangered) are also present at higher altitudes.

Native ground-nesting birds breed on the short-statured or sparsely-vegetated outwash plains, wetlands and in braided riverbeds over the spring-early summer period. Loss of habitat and the introduction of mammalian predators led to kaki/black stilt numbers plummeting and the species was on the verge of extinction when the Wildlife Service launched a successful recovery programme in 1981.

The recovery programme is focused on protecting eggs and chicks from predation through captive rearing and release, and predator/habitat management at main sites as a key component in the bird’s recovery. The population has gradually increased over the last 37 years, with more than 130 kaki in the wild now (compared with lows of 23 in 1980, and 31 in 1999).

Fish and other species

The diverse mosaic of braided river, wetland (i.e. fens, bogs, marshes, ephemeral, kettle holes and swamps) and lake ecosystems provide important habitat for freshwater fish, including threatened species and freshwater invertebrates. There are ten threatened or at-risk fish species in the Waitaki Catchment including the inanga and tuna (long-finned eel) whose numbers have declined.

Approximately 30 terrestrial invertebrates are also threatened or at risk. Many of these are either endemic or the Basin is their stronghold. The native ‘robust grasshopper’ is only found in the Mackenzie. The large, distinctive grasshopper doesn’t hop well and therefore tends to hide in the braided riverbeds, where its grey-brown coat provides camouflage.

Additionally, the Basin is home to five threatened or at risk lizard species.

Plants

Approximately 200 threatened, at risk and data-deficient plant species occur in the Waitaki catchment of which 109 occur in the ‘Mackenzie Dryland’ zone. Many of these species are endemic to the Mackenzie Basin, or specific habitats within the Basin, or are dryland species with their national stronghold in the Basin.

Biosecurity - introduced pests and their management

European settlement introduced numerous plant and animal pests to the Mackenzie, all of them flourishing in the landscape and harmful to the indigenous ecology.

The plants include gorse and broom, wilding conifers, lupins, Cotoneaster and Hieracium (hawkweed). The animals include rabbits and hares, ferrets, stoats and feral cats, which were initially introduced as domestic pets. Black-backed gulls, Canada goose, hedgehogs, rats, mice, possums, tahr, deer are also pests.

Environment Canterbury’s Regional Pest Management Plan involves working with the Department of Conservation on controlling rabbits, wallabies, crack willow infestations, wilding conifers and cotoneaster to protect habitats.

The Department of Conservation’s Project River Recovery in the Mackenzie Basin has removed thousands of willow trees from braided rivers and widespread spraying of lupins, gorse and broom and other weeds in the Tekapo, Ahuriri and Pukaki Rivers, along with the creation of wetlands.

DOC is also one of the founding partners of Te Manahuna Aoraki, a new programme chaired by former Commissioner for the Environment Dr Jan Wright.

The programme aims to restore the iconic natural landscapes and threatened species of the Mackenzie by removing introduced pest and predator species. Founding partners include the Department of Conservation, NEXT Foundation, Te Rūnanga o Arowhenua, Te Rūnanga o Waihao and Te Rūnanga o Moeraki. They are joined by high country runholders, Land Information New Zealand (LINZ), the Ministry of Defence, and other philanthropists.

Te Manahuna Aoraki aims to secure a vast pest and predator-free mainland island, 310,000ha in size.

The site includes New Zealand’s highest mountain Aoraki Mt Cook, which along with neighbouring mountain ranges will protect and enclose two-thirds of the project area from most reinvading pests.

Within the site lies Lake Pukaki and Lake Tekapo and the extensive braided river systems that feed them. At the southern end of the valleys runs the Tekapo hydro canal which offers a potential defensive line for some of the area perimeter, with predator-proof fencing also being investigated.

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