The health of Porirua Harbour has dropped to the point where it is no longer safe for swimming or seafood gathering, a new report shows.
Prepared by NIWA and funded by the Greater Wellington Regional Council, it is the first stage of a three-part study by Ngati Toa to establish a base for monitoring of the harbour.
"To care for the harbour effectively we need first to fully understand what we have done to it over the years and to truly appreciate what we have lost," Ngati Toa spokesperson Jennie Smeaton said.
"We have all heard the stories and now we have backed these up with historical and scientific information. In this way we hope to be able to work to restore what we once had and leave behind the lessons we have learned along the way."
Ngati Toa have occupied the harbour since 1890, enjoying an abundance of pipi or cockle, green-lipped mussels and oysters, grey mullet, flounder, kahawai, conger eel, snapper, rig, school shark, and yelloweyed mullet.
The Onepoto Arm was the main food basket.
The harbour was also important as a playground and had spiritual significance.
Some of the 13 kaumatua interviewed for the study were baptised in the harbour, and recalled that baptisms often occurred there.
From the mid-1950s, the reclamation of tidal flats, straightening of the Kenepuru Stream, increasing pollution and sedimentation, and increasing housing development and population growth impacted on the Onepoto Arm.
The harbour's health decreased significantly, access to kai moana diminished, and the abundance of fish and shellfish declined.
By the mid-1960s most of the shellfish gathering and fishing had ceased altogether due to pollution.
Porirua Harbour is regularly featured in lists of the most polluted waterways in the Wellington region.
In May last year, bacteria levels in the harbour rose to more than triple the level considered safe for swimming.
"Through this study and with the help of a highly regarded scientific institution, Ngati Toa has confirmed our belief about the harbour and established how best we can work alongside NIWA and other stakeholders to restore it back to a place to play and collect kai moana," Ms Smeaton said.
Stage two of the study is now underway.
It will record the species that visit or visit the harbour.
A report is due at the end of the year.
- © Fairfax NZ News
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