In the past, many New Zealanders have not understood the value of estuaries. Many European settlers initially viewed estuaries as unproductive wastelands. Land was reclaimed for harbours and filled in for pasture, sewage schemes and rubbish dumps. Māori viewed estuaries as productive food gardens and often actively protested when sewage and stormwater were discharged into estuaries. Their spiritual and cultural dimensions gave them insight into the need to protect and care for their food baskets. Ngāti Pikiao claimants in their Kaituna River claim stated that “to mix waters that had been contaminated by human waste with waters that were used for gathering food was deeply objectionable” (Waitangi Tribunal claim, 1984).

The passing of the Resource Management Act in 1991 required local authorities to manage estuaries and other coastal areas in a sustainable manner and respect Māori cultural and spiritual values concerning these areas.

The wider New Zealand population is now beginning to understand and appreciate the significance of estuaries. We are learning that healthy estuaries benefit us and deserve care and protection. We are realising estuaries have ecological, economic and cultural value.

Ecological value

Estuaries contain a rich biodiversity of life – said to be the nurseries of oceans. They are one of the most productive ecosystems on Earth – playing an important and complex role in the life of the coast. Their habitats are critical to the survival of many species. Thousands of fish, birds and other wildlife use estuaries to live, feed and reproduce. Many species use estuaries as nurseries to spawn and as a place for juveniles to grow.

Estuaries maintain water quality through natural filtration. Surrounding marshes and plants help to filter out pollutants and sediments carried in through water drainage from the land. Wetland soils and plants such as mangroves act as a natural buffer between land and sea, absorbing floodwaters from the land and storm surges from the sea.

Economic value

Estuaries have commercial value to fishing industries. Fish and shellfish use estuaries to spawn their young, and their juveniles are sustained in estuaries until they are able to move away, either out into the ocean or up rivers. Estuaries maintain water quality – benefiting people and marine life. They are ideal places for boats or ships to come in to land and so are used for transport. Industry is often set up near estuaries for ease of transportation of goods (for example, fisheries and timber). Estuaries are tourist attractions – attracting overseas visitors as well as local New Zealanders.

Cultural value

Māori have always valued estuaries as a sought-after resource. Nearby timber was used for building and could be easily transported by water in the estuaries. Plants were used for rongoā (medicine), harakeke (flax) for weaving, and kai (food) included birds, eels, fish, rats and shellfish. Villages were often established near estuaries for easy access to these resources.

Eels were an important part of the Māori diet. They were often caught in special traps at the estuary (when eels were migrating) and then filleted and dried in the sun. Many Māori today continue to collect their kaimoana from estuaries. For a number of coastal Māori, this is their main source of food.

People today value estuaries for recreation such as swimming, boating, fishing and bird watching. The unique habitats of estuaries make them of interest to scientists and students for studying and developing knowledge. Many estuaries were once seen as ‘dirty mudflats’ to be avoided. People now appreciate the aesthetics of estuaries – the unique biodiversity of life and tranquil settings.

Estuaries provide us with resources, benefits and services that improve our lifestyle. It is difficult to put a monetary value on these benefits. Estuaries are natural resources that need to be carefully looked after and protected for the mutual benefit of all who enjoy and depend on them.

Nature of science

Science is a way of explaining the world, and science knowledge changes over time. This is true for the science knowledge and mātauranga surrounding estuaries. The more we have come to understand estuaries and their place in the world, the more we have come to value them.

    Published 12 June 2017