Pukerua Bay’s flourishing marine life has always been a drawcard. It provided abundant kai moana for the Māori who built their kāinga and pā here, and its bounty also drew the pakeha who built the smattering of baches that appeared along the beachfront from the early twentieth century. Nowadays, with a boutique form of marine protection that prohibits certain fishing methods and catches in the inshore area while allowing line fishing to continue, recreational fishing remains a hugely popular activity that’s a central part of the Pukerua Bay lifestyle.

Pukerua Bay straddles the transition zone between the long, uninterrupted sandy Manawatu and Kapiti beaches, and the mostly rocky Wellington coastline. The first rocky reefs appear near the Fisherman’s Table restaurant at Paekakariki as a fringe of inshore rocks that fade into a sandy seafloor no more than about a hundred metres from the shore. Approaching Pukerua Bay, the rocky seabed extends further offshore, with shallow (ten metres or less deep) rocky reefs extending approximately a kilometre to the north of Ocean Parade before dropping onto the sandy, gravelly seabed that extends almost all the way to Kapiti Island. West of our beaches, continuing around past Wairaka Point and southwards beyond that, the close inshore environment is almost exclusively rocky, with some quite spectacular pinnacles rising from depths or twenty to thirty metres (and even deeper, further offshore) to within about ten metres of the surface. Hunter Bank, nine kilometres out to the northwest of our beach is the largest of these pinnacles, with its peak about 15 metres below the sea surface and its base around 50 metres deep.

Strong tidal currents sweep the area, running generally towards the south on an ebbing tide and towards the north as the tide rises. Alternately the tides bring nutrients from the deep, cold waters of Cook Strait and warmer water from the South Taranaki – Manawatū coast. The abundant phytoplankton (minute plant life) and zooplankton (equally minute animal organisms) borne by those currents form the basis of a food chain that supports rich marine diversity here. Equally, the ebbing tidal sometimes carries large amounts of silt, originating from the large rivers to the north of us, particularly the Whanganui and the Manawatu when they are in flood. The three small streams that drain into our bay also contribute silt during heavy rain. The silt often accumulates as a thin layer over inshore seaweeds and deeper reefs, but its effect on encrusting marine life appears to be minimal. A much more significant impact is the reduction in water clarity – and sunlight penetration – when the water is cloudy with suspended silt, as it mostly is. As a result of the generally poor underwater visibility and light penetration, seaweeds – which, like plants, depend on sunlight for their growth – are only present here in water less than about four to six metres deep (compared with ten metres or more at Kāpiti Island, which is far enough offshore to escape the worst of the coastal silt flows). However, while light dependent seaweeds are restricted to shallow water at Pukerua Bay, the reduced lite levels and abundant planktonic life forms are ideal for deeper water encrusting species, such as sponges and bryozoans, that are spectacularly abundant in places off Pukerua Bay in depths beyond about ten metres.

The following list of species is based predominantly on my own observations, as a longtime shoreline fossicker, diver and a fisher, plus a few reported to me by others. I have mostly used their common names, rather than scientific names, partly because that is what most of the community will know them by, but also because scientific names tend to change from time to time as the classification of species is refined.

Because my knowledge of marine algae (seaweeds) is limited, that part of the list is brief and generic. Undoubtedly there will be others reading this who will be able to contribute more information on these.