Westhaven (Te Tai Tapu)

Westhaven (Te Tai Tapu) Marine Reserve protects 5.36 square kilometres of estuarine and coastal waters within Whanganui Inlet, a large, sheltered tidal inlet on the remote north-western coast of the South Island in the Tasman region. ^[1] Established in 1994 and managed by the Department of Conservation, the reserve safeguards one of the least modified estuarine systems in New Zealand, described as the first estuary in the country to have everything from the land to the sea protected by a combination of marine and wildlife reserves. The Maori name Te Tai Tapu — meaning sacred waters or sacred coast — reflects the area's deep cultural significance. With its extensive tidal flats, channels, seagrass beds and surrounding forested hills, the reserve protects a tranquil and ecologically rich inlet near the small settlement of Collingwood in Golden Bay.

The sheltered inlet supports a productive estuarine ecosystem rich in fish and invertebrates. At least 30 marine fish species use the inlet for some stage of their life cycle, with snapper, flatfish and kahawai using it as a breeding and nursery area. ^[1] Shellfish such as cockles, pipi and mussels inhabit the tidal flats and channels. The reserve and surrounding wildlife management area are important for birdlife, with approximately 42 water bird species recorded in the inlet, including wading birds, shags, herons, oystercatchers and waterfowl feeding on the rich tidal flats. The undisturbed nature of the inlet supports healthy populations of estuarine invertebrates that form the base of the food web and sustain both fish and bird communities.

The inlet's marine flora is dominated by extensive seagrass meadows and estuarine algae that thrive in its sheltered, nutrient-rich waters. Seagrass beds stabilise the sediment, provide nursery habitat for fish and invertebrates, and support feeding birds. Salt marsh vegetation, including rushes and saltmarsh plants, fringes the tidal margins, grading into the surrounding native forest of the wildlife management reserve. Mudflat and sandflat communities host benthic algae and microalgal films that fuel the estuarine food web. This combination of seagrass, salt marsh and intertidal algae makes the inlet one of the most intact and ecologically valuable estuarine plant communities on the coast.

Whanganui Inlet is a drowned river valley, formed where rising sea levels flooded a low-lying coastal basin to create a large, sheltered tidal inlet behind a barrier of dunes and headlands. ^[1] The inlet is approximately 13 kilometres long and 2 to 3 kilometres wide, with the seafloor dominated by soft sediments, including mud, sand and shell, deposited within the calm, tidally flushed waters, with channels carved by tidal flow. The surrounding hills are composed of older sedimentary and basement rocks mantled by native forest. This geomorphology of a sheltered, sediment-filled inlet, with its tidal flats, channels and fringing wetlands, gives the reserve its distinctive estuarine character, quite different from the open rocky coastlines of most marine reserves.

The reserve lies in a wet, mild maritime climate on the exposed north-western coast of the South Island, where prevailing westerly weather brings high rainfall and frequent cloud. Summers are mild and humid, winters cool, and the surrounding hills are often wet, feeding fresh water into the inlet. Although the open coast is exposed to strong westerlies and heavy swells, the inlet itself is sheltered, with its tidal flats and channels protected from the worst of the ocean weather. Water temperatures in the shallow inlet are moderated by tidal exchange and freshwater inflow, and the area's wet climate sustains its lush surrounding forest and productive estuarine system.

The name Te Tai Tapu signifies the deep cultural importance of this coast to Maori, for whom the inlet and surrounding lands were valued for fishing, shellfish gathering and travel along the remote western coast. The rich estuarine resources sustained communities of Ngati Rarua, Ngati Tama and Te Ati Awa, the iwi groups with historical ties to the inlet, and the area retains significant cultural and historical associations. ^[1] European history in the region includes nineteenth-century exploration, gold mining nearby in Golden Bay, and small-scale timber milling and farming on the inlet's margins. The relative remoteness and difficult access of the north-western coast meant the inlet escaped much of the development seen elsewhere, helping to preserve its natural character into the present day.

Westhaven (Te Tai Tapu) Marine Reserve was established in 1994 under the Marine Reserves Act 1971 to protect the largely unmodified estuarine ecosystem of Whanganui Inlet, recognised as one of the most intact inlets of its kind in New Zealand. ^[1] The reserve was created alongside the Westhaven (Whanganui Inlet) Wildlife Management Reserve, providing complementary protection of the marine waters and the surrounding land, wetlands and forest, and together forming the first estuary in New Zealand to be protected from land to sea by this combined approach. The Department of Conservation has since managed the reserve as a no-take area, conserving its seagrass beds, tidal flats and the rich bird and fish communities they support.

The reserve's attractions centre on its tranquil estuarine setting, abundant birdlife and unspoilt scenery rather than diving, given its sheltered, shallow and often murky tidal waters. Visitors can explore the inlet by kayak or small boat, taking in the seagrass flats, channels and forested shores, and observe wading birds and waterfowl feeding on the tidal flats. The surrounding Westhaven wildlife reserve offers coastal walking and birdwatching opportunities, while the remote, scenic drive to the inlet along the wild north-western coast is an attraction in itself. The area's quiet remoteness and ecological richness appeal to those seeking nature and birdwatching rather than busy tourist destinations.

Access is via the small settlement of Collingwood in Golden Bay, with the inlet reached along a winding, partly unsealed road to the remote north-western coast. ^[1] There are no developed facilities within the marine reserve, and visitor services are limited; the nearest amenities are at Collingwood and surrounding Golden Bay communities. Boats may be launched at Mangarakau Wharf, though crossing the Westhaven sand bar requires experienced seamanship and caution. The inlet can also be explored by kayak or small boat. Visitors should be prepared for a remote, undeveloped area with changeable weather, and must observe that all fishing and shellfish gathering are prohibited within the marine reserve boundaries.

As a no-take marine reserve, Westhaven (Te Tai Tapu) prohibits fishing and shellfish gathering, protecting the intact estuarine ecosystem of Whanganui Inlet and allowing its fish, shellfish and bird populations to flourish undisturbed. ^[1] The reserve's pairing with the adjoining wildlife management reserve safeguards both the marine waters and the surrounding wetlands and forest, conserving a complete catchment-to-sea system — the first of its kind in New Zealand. Its value lies in being one of the least modified estuarine inlets in the country, a benchmark for healthy estuarine function. Conservation priorities include maintaining water quality and freshwater inflows, protecting seagrass beds and tidal flats from disturbance and sedimentation, and controlling pests in the surrounding land reserve.