Estuaries were favoured food-gathering spots and sites for settlement for the early Polynesian settlers. They remain significant areas for fishing and shellfish harvesting.
Estuaries provided safe, sheltered waters with an abundance of fish, shellfish and birds for eating. Middens (ancient refuse heaps) have been found in every sheltered coastal site around New Zealand and are especially common around northern harbours with large shellfish beds. Estuarine rivers gave access to the interior of the country and its wealth of resources – tall-timbered rain forests, abundant bird life, flax swamps and rivers full of eels.
When European settlers began arriving in the early 19th century, like Māori they were attracted to estuaries. The large estuaries made excellent natural harbours; cities and towns like Whāngārei, Auckland, Tauranga, Napier, Wellington, Lyttelton, Dunedin and Bluff soon developed around them because transport in the developing colony was predominantly by coastal shipping. Small ports sprang up in practically every harbour in Northland and the Coromandel in the 1860s, as settlers stripped the land of its kauri timber and gum and shipped them to large ports at Auckland (Waitematā Harbour) and Onehunga (Manukau Harbour).
Shipping on the Avon–Heathcote
The colonial founders of Christchurch relied on the Avon–Heathcote estuary for transport and trade for the first 20 years of settlement. Until the Lyttelton rail tunnel opened in 1867, small vessels (schooners, yachts, whaleboats) ferried people and goods across the sand bar and up to the Barbadoes Street bridge on the Avon River, or to Wilson Bridge on the Heathcote River. As settlers cleared and drained the land, the rivers clogged up with sediment. By 1900 the Avon was less than 10 centimetres deep in many places.
Food supply or dumping ground?
Because estuaries were viewed by many European settlers as unproductive wastelands, estuarine land was reclaimed for harbours, and filled in for pasture, sewage schemes and rubbish dumps. Māori never accepted this view and actively protested when sewage and stormwaters were discharged into estuaries. A number of claims to the Waitangi Tribunal focus on the destruction of traditional estuarine food-gathering areas. The spiritual and cultural dimensions of Māori objections were expressed by Ngāti Pikiao claimants in their Kaituna River claim, which stated that ‘to mix waters that had been contaminated by human waste with waters that were used for gathering food was deeply objectionable’. 1
Since the passing of the Resource Management Act in 1991, local authorities have been required to manage estuaries and other coastal areas in a sustainable manner and respect Māori cultural and spiritual values.
Threats to estuaries
Notwithstanding the Resource Management Act 1991, many estuaries remain vulnerable to harmful influences. The major threats are:
- excess silt flowing in from land clearance
- pollution from sewage, industrial wastes and agricultural run-off
- oil spills
- invasion by introduced species
- reclamation for marinas
- extraction of sand and gravel.
These activities decrease the habitat available for estuarine plants and animals, spoil recreational activity in the area, and jeopardise the role estuaries play in maintaining the health of coastal fisheries and waters.
Why value estuaries?
The estuary plays an important and complex role in the life of the coast, acting as:
- a breeding and feeding ground for fish and birds
- a buffer for the coast from storms and floods
- a filter for sediments and pollutants from coastal waters
- a record of past environments and events
- a place for recreation (such as water sports, fishing, shellfish gathering, duck shooting, birdwatching)
- a site for marine farms.
In the past, many New Zealanders failed to appreciate the value of estuaries, as their life in the towns and on farms seemed to be independent of the state of coastal waters. But with an expanding population demanding clean water for recreation and aquaculture, people are learning that healthy estuaries are an asset and deserve careful management.