Wetlands & Water Quality

In the recent times there have been many articles written and published about water quality and wetlands and in one of the most recent articles Forest & Bird freshwater advocate Annabeth Cohen said not enough is being done to protect what's left of the nation's wetlands

"We aren't doing a very good job of protecting what's left."

Wetlands played a vital ecological role and provide unique habitat for threatened plants, birds, and fish, they also improved water quality, and reduced flood risks to nearby communities.

She also goes on to state:

"The Department of Conservation is responsible for managing our Ramsar sites, but in cases like the vast Whangamarino wetland in the Waikato, their efforts are hampered by poor management from [the] regional council."

The Whangamarino wetland is affected by sediment from a number of sources, including adjacent farmland.

Well I am afraid that this (protection of the remaining wetlands) is a battle that we do not have a chance of winning under the current system.

The current focus is totally on the agricultural sector and even if we stopped all types of agricultural land use tomorrow the wetlands and water quality will continue to degrade at an ever increasing rate due to the effects from Koi Carp.

The Department of Conservation website classes them as a noxious pest and states that:

“When they feed they stir up the bottom of ponds, lakes and rivers, muddying the water and destroying native plant and fish habitat. Koi carp are opportunistic omnivores, which means they eat a wide range of food, including insects, fish eggs, juvenile fish of other species and a diverse range of plants and other organic matter.

They feed like a vacuum cleaner, sucking up everything and blowing out what isn’t wanted. Aquatic plants are dislodged in the process and are unlikely to re-establish. Koi carp cause habitat loss for plants, native fish, invertebrates and waterfowl and they are highly tolerant of poor water quality and contribute to water quality decline.

While there can be no argument over her contention that development has destroyed the majority of the wetland areas in New Zealand it is our contention that the majority of the ongoing degradation problems with the Whangamarino wetland is in fact due to the effects of the pest fishes such as Koi Carp and this is supported by the results of water quality sampling that was recently commissioned by the Primary Stakeholders Catchment Trust from the Lake Waikare-Whangamarino Catchment.

The results showed that the major problem was with the levels of sediment and phosphorous not nitrates and that the levels were far greater at the discharge end of the wetlands than they were at the entry point from this catchment.
This supports our contention that the problems are being greatly exacerbated within the boundaries of the wetland itself and that the only reasonable explanation for this can be the effects of the pest fishes.

Koi Carp in the New Zealand environment have no natural predators and this fact coupled with their extremely high breeding success rate means that they are an extremely dangerous pest in relation to our lakes, rivers and wetlands.

Yet the Waikato Regional Council (WRC) in the current proposed plan change (PC1) under the Healthy Rivers project has no mention of Koi Carp or any control measures to reduce the effects from them.

It is estimated that there are approximately 500,000 tonnes of Koi Carp in the lower Waikato and Waipa lakes, rivers and wetlands and yet the WRC persist in ignoring the effects from these pests in PC1 with a total focus on the agricultural sector as being solely responsible for the decline in water quality across the Waikato region.

Yes agriculture does have an impact on the water quality along with urban development but over the last two decades agricultural land users have made major improvements to operating methods that have reduced the nutrient loading being put directly into waterways.

Whilst there are still more improvements to be made, without controlling the rapidly increasing numbers of Koi Carp in the waterways we are looking at having an ongoing problems with erosion of the banks of the waterways, declining water quality and the extinction of most native species in the waterways due to the omnivorous feeding methods of the Koi Carp.

Under the Under the Vision & Strategy contained in schedule 2 of Waikato-Tainui Raupatu Claims (Waikato River) Settlement Act 2010, Part 1 Vision, Section k) requires: the restoration of water quality within the Waikato River so that it is safe for people to swim in and take food from over its entire length:

Without addressing the issue of pest fishes there will be a severe detrimental effect on the ability of all people to take food from the rivers due to the effects from the Koi Carp.

There is another issue that has a huge effect on the water quality in the Whangamarino wetland and that is the weir on the Whangamarino River that was installed under a resource consent jointly applied for by the Department of Conservation and Fish and Game. This consent was granted and the weir built and since then the conditions of the consent have not been adhered to.

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