Porirua Harbour Trust

Discover the Harbour

Plants and Animals

 The Porirua Harbour and Catchments Community Trust
known as the Porirua Harbour Trust (PHT)

Plants and animals of the Porirua Harbour

Harbour formation

Porirua Harbour, including the Pāuatahanui Inlet, is one of New Zealand’s most important estuarine environments. Its tidal flats, marshes, shallow waters, and surrounding vegetation support a wide range of plants and animals. This page provides an overview of key species found in the area

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Fish Species

Pāuatahanui Inlet and the wider Porirua Harbour act as nursery areas and habitats for many fish species. Around 46 species have been recorded in the harbour

  • Yellow-eyed mullet, Aldrichetta forsteri, Common resident; found throughout the inlet.
  • Sand flounder, Rhombosolea plebeia, Abundant flatfish species; uses inlet as a nursery area.
  • Dwarf common sole, Peltorhamphus latus, Resident species of shallow estuarine waters.
  • Spotty, Cheilodactylus kumu, Common around harbour structures; feeds on small invertebrates.
  • Common triplefin, Trypterygion robustum, Widespread reef and rocky-shore fish.
  • Garfish, Hemirhamphus ihi, Common surface-feeding fish; forms schools.
  • Whitebait (Inanga), Galaxias maculatus, Migratory species that uses inlet-feeding streams.
  • Banded kokopu, Galaxias fasciatus, Occasional sightings in streams connected to the inlet.
  • Rig (juvenile shark), Mustelus lenticulatus, The harbour is an important nursery for this species.
  • Kahawai, Arripis trutta, Common in harbour waters, often chasing baitfish.

Birds

The inlet is a major feeding and roosting site for waders, waterfowl, and migratory birds. Around 50 bird species are regularly observed.
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  • Black Swan, Cygnus atratus, Feeds on seagrass; common in deeper channels.
  • Mallard, Anas platyrhynchos, Common duck around marsh edges and open water.
  • Paradise Shelduck, Tadorna variegata, Often in pasture edges and wetland areas.
  • Royal Spoonbill, Platalea regia, Feeds in tidal flats using sweeping bill motion.
  • Pied Stilt, Himantopus himantopus, Very common wader on mudflats.
  • Oystercatcher (Variable), Haematopus unicolor, Feeds on shellfish along intertidal zones.
  • Little Shag, Phalacrocorax melanoleucos, Often seen perched on posts drying its wings.
  • White-faced Heron, Egretta novaehollandiae, Very common; feeds in shallow water.
  • Pukeko (Australasian Swamphen), Porphyrio melanotus, Common in wetland vegetation.
  • Bar-tailed Godwit, Limosa lapponica baueri, Migratory species that arrives during the summer.

Crustaceans & Invertebrates

The inlet’s mudflats and tidal zones are rich with shellfish, crabs, worms, and other invertebrates. These species provide essential food for fish and birds

  • New Zealand cockle, Austrovenus stutchburyi, Abundant filter feeder; important food source for birds.
  • Mud snail, Potamopyrgus antipodarum, Common on mudflats and marsh edges.
  • Mud crab, Austrohelice crassa, Visible at low tide; builds burrows in mudbanks.
  • Polychaete worms, Multiple species, Numerous worm species living within the sediment.
  • Meiofauna (e.g., copepods), Various species, Microscopic invertebrates crucial to nutrient cycling.
  • Priapulid worms, —, Small burrowing worm species found in inlet mud.

Plants

The plant life around the inlet includes saltmarsh vegetation, seagrass beds, algae, and the surrounding wetland and forest-edge species

  • Saltmarsh, Glasswort (Sarcocornia), Sea Rush (Juncus spp.), Salt-tolerant plants that stabilise the shoreline.
  • Seagrass Beds, Zostera novazelandica, Provides nursery habitat for juvenile fish.
  • Algae, Sea Lettuce (Ulva lactuca), Common in summer; can form large green mats.
  • Wetland vegetation, Harakeke (Phormium tenax), Raupō, Sea Primrose, Found along edges of the inlet and streams.
  • Coastal forest fringe, Kānuka, Mānuka, Ngaio, Regenerating coastal forest and shrubland.

Why This Matters

The harbour provides a:

  • Nursery habitat: The inlet provides safe, sheltered waters for juvenile fish (e.g., flounder, rig), which later move out to sea. Greater Wellington
  • Bird feeding grounds: The tidal flats and marshes are rich in invertebrates, supporting a wide variety of wading and water birds. Guardians of Pāuatahanui Inlet+1
  • Ecosystem health: The dense cockle beds filter huge volumes of water every tide, helping maintain water quality. Guardians of Pāuatahanui Inlet
  • Biodiversity conservation: Native plants like harakeke, sea rush, and coastal forest species help anchor the ecosystem and provide habitat. Explore Wellington

What we can do

Porirua Harbour, including the Parumoana (Onepoto) arm and Pāuatahanui, Inlet faces a number of environmental threats:

  • Pollution & Runoff: Urban stormwater brings sediments and contaminants into the inlet. (Guardians of Pāuatahanui Inlet)
  • Eutrophication: Nutrient inputs (e.g., from fertilizers or sewage) can spur algae growth, which can smother seagrass beds. (Guardians of Pāuatahanui Inlet)
  • Habitat Loss: Development around the inlet can degrade or destroy saltmarsh, forest fringe, and other critical habitats. (Doc.govt.nz)

To protect this ecosystem, local groups like Guardians of Pāuatahanui Inlet (GOPI), Wellington Regional Council, Porirua City Council, and DOC are working together on restoration projects: removing invasive species, restoring native plants, and improving land-use practices. (Guardians of Pāuatahanui Inlet, Coastal Restoration Trust)

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