Paterson Inlet/Whaka ā Te Wera is a shallow ria – an ancient river valley that has been submerged – and provides one of the largest sheltered harbours in southern New Zealand.
Because the rivers that flow into it drain from pristine, undeveloped land, they carry little sediment or nutrient run-off. As a result, inlet waters nurture a prolific range of plants and animals.
Paterson Inlet is also an important habitat and nursery for at least 56 species of marine fish. The mixing of warm, subtropical and cool waters in the currents around Stewart Island/Rakiura has created an environment with similarities to both regions, and adds to the diversity of species found within the inlet.
The inlet is home to brachiopod species that live both on rock and sediment, thriving at depths of less than 20 m. This makes it one of the richest and most accessible brachiopod habitats in the world. Brachiopods (lamp shells) are the most ancient of filter feeding shellfish. They were abundant in prehistoric oceans 300 to 550 million years ago. Today their fossils are common but living examples are comparatively rare.
Stewart Island/Rakiura has more varieties of seaweed than anywhere else in New Zealand. Paterson Inlet is home to 70% of them, including 56 brown, 31 green and 174 red species. Meadows of small red seaweed grow on the sand. They help to stabilise sediment as well as providing an important shelter for scallops, and a surface for spat to settle on.
The marine reserve is surrounded by Paterson Inlet/Whaka ā Te Wera Mātaitai Reserve. The mātaitai reserve prohibits commercial fishing and manages recreational fisheries levels to ensure the sustainability of important traditional Māori fishing and food gathering areas.