Mangawhai mangrove clearing rejected

09 May 2011

By Marine Advocate Karen Baird

A resource consent hearing last month rejected a proposal to rip out all of the mangroves in the Mangawhai Harbour, an area which supports half the breeding population of the critically endangered New Zealand fairy tern.

The Mangawhai mangroves are an important site for our critically endangered Fairy Tern. Photo: Rob Suisted.

The Mangawhai mangroves are an important site for our critically endangered Fairy Tern. Photo: Rob Suisted.

The proposal came from a local group called the Mangawhai Harbour
Restoration Society (MHRS), which has previously been involved in dredging
the harbour mouth and planting on the Mangawhai Sand Spit – a wildlife
refuge.

This has brought them in to conflict with groups including Forest
& Bird, which is concerned about this important breeding area for coastal
birds, which mostly do not like nesting near vegetation.

Mangawhai, which lies north of Auckland, is the single most important place in the
country for the fairy tern. It supports half the total breeding population of just 8-10
pairs.

The preliminary results of Forest & Bird’s study of the feeding habits of
breeding fairy terns last summer showed the birds feed mainly in the upper part
of the harbour in areas where the shore is lined with mangroves and fish density
is greater.

The birds feed mainly at low tide, when the area is generally free from the considerable boat traffic which coincides with the summer breeding period.

The MHRS proposal involved clearing all 85 hectares of mangroves and
burning them on site, dredging up to 1.7km of the upper harbour channel
and dumping dredge spoil to create beaches.

The growth of mangroves has followed the build up of sediment in
the harbour and the three independent commissioners at the resource consent
hearing said this had been greatly facilitated by the building of two road
causeways across the upper estuary.

Despite this, the commissioners rejected submissions that the current
extent of mangroves in the harbour should be not be included as part of the
harbour’s natural character.

“A dislike of mangroves cannot legitimately, in our view, translate into a
conclusion that mangroves are neither natural, nor an intrinsic component of
the harbour’s natural character.”

One disturbing comment by the commissioners was that a more modest mangrove removal proposal
for Mangawhai Harbour may be appropriate.

If there are to be any further proposals for mangroves clearance, proponents
should meet with Forest & Bird and other concerned groups to develop
an acceptable proposal that includes appropriate measures for reducing
sediment flows into the harbour.

It is clear from Forest & Bird’s research that any interference with the most
significant feeding grounds for the NZ fairy tern could spell disaster for the
bird’s long term survival.