Only San Francisco harbour is bigger than the Kaipara Harbour. And the Kaipara has the longest shoreline of any harbour in the world. I grew up near the Northern Wairoa river that flows into the north end of the Kaipara. The water is brown, drenched in colloidal sediment that doesn’t settle. I was told the sailing ships used to access fresh water from the mouth of the Kaihu stream at Dargaville, but those days are long gone.
Forests have been stripped off the lands in the Kaipara’s massive catchment leading to erosion that continues today. Thankfully we have moved beyond the days when farmers could get subsidies for breaking in marginal land. But the sediment loads in the Kaipara continue to increase by 10mm a year according to this excellent article by Lois Williams.
As a consequence, snapper in the harbour are mutating as their gills adapt to handle the heavy loads of sediments. And the Kaipara harbour is a snapper nursery for the whole of the west coast.
The Kaipara catchment, stretching from the Waitakeres in the south to Waipoua in the North and the eastern hills to the north of Whangarei. (image from the Integrated Kaipara Harbour Management Group website).
The sediment problem was reversed in the Whāingaroa (Raglan) harbour. When streams were fenced off and planted, sediment flows slowed down. The invertebrates at the base of the food chain returned enabling the repopulation of kaimoana.
Revegetating the huge Kaipara catchment is a much more daunting task, but progress is being made. The Integrated Kaipara Harbour Management Group has overseen the planting of 2 million trees over the last decade. This is a impressive partnership of local government, Iwi and hapu (Ngati Whatua and Te Uri o Hau), Fonterra, Government Agencies and NGOs. There efforts will also be sequestering a significant amount of carbon. Their guiding principles are:
- Integrated Ecosystem-Based Management
- Manaakitanga respect
Kia ora and thank you to them!
The Pouto lighthouse at the mouth of the Kaipara harbour (photo by Joanne Watkinson)