Proposed Waikato Regional Plan Change 1
Waikato and Waipa River Catchments
Koi Carp Issues
The Healthy Rivers: Plan for Change/Wai Ora: He Rautaki Whakapaipai project Vision and Strategy required the development
of a plan for the rivers to be swimmable and safe for food collection.
The change to the Operative Waikato Regional Plan (WRP) is designed to restore and protect water quality in the Waikato
and Waipa Rivers by managing nitrogen, phosphorus, sediment and microbial pathogen levels in the rivers.
The Vision and Strategy states that the Waikato and Waipa Rivers are degraded and require restoration and protection and
that one method for this will be provided by ongoing management of diffuse and point source discharges of nitrogen,
phosphorus, sediment and microbial pathogens.
Yet arguably the largest contributor to sediment loading in the rivers is ignored in this plan change – KOI CARP!
The plan change document includes the table shown below:
Ecosystem health
The Waikato and Waipa catchments support resilient freshwater ecosystems and healthy freshwater populations of
indigenous plants and animals.
• Clean fresh water restores and protects aquatic native vegetation to provide habitat and food for native
aquatic species and for human activities or needs, including swimming and drinking.
• Clean fresh water restores and protects macroinvertebrate communities for their intrinsic value and as a food
source for native fish, native birds and introduced game species.
• Clean fresh water supports native freshwater fish species.
• Wetlands and floodplains provide water purification, refuge, feeding and breeding habitat for aquatic species,
habitat for water fowl and other ecosystem services such as flood attenuation.
• Fresh water contributes to unique habitats including peat lakes, shallow riverine lakes and karst formations
which all support unique biodiversity.
• Rivers and adjacent riparian margins have value as ecological corridors.
Koi carp contribute to poor water quality and are a serious problem in both Australia and New Zealand.
What damage do they do?
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.
Koi Carp can produce approximately 14 times their own body weight of sediment each year through this feeding method. It
is estimated that there are approximately 500,000 tonnes of Koi Carp in the Auckland/Waikato region.
Where are they found?
Koi carp prefer still waters in lakes, or backwaters in rivers. They are highly tolerant of poor water quality and
contribute to water quality decline.
Koi Carp have no natural predators in the New Zealand environment and when this fact is coupled with a breeding success
rate of approximately 99% this shows why they have been able to multiply and spread across the regions so rapidly.
Koi carp are widespread in Auckland and Waikato. They are spreading into Northland and they have been found in isolated
places in Whanganui, Hawke's Bay and Wellington. Koi carp have been illegally released in the Nelson/Marlborough area.
Breeding
Waikato koi rarely exceed 9 years of age. Females average 5.2 years and males 4.6 years of age. An average fish weighs 3
kg. Females produce 100 000 eggs per kg of body weight. A typical female can produce 300 000 eggs annually (or more if
they spawn more than once). Koi carp spawn throughout the summer. As they gather for spawning or feeding in the shallow
margins of the river, koi biomass can reach 4000 kg/ha.
Koi carp breed prolifically with a single fish laying between 800,000 to 1 million eggs.
Once established in an area they have a huge and significant impact on rivers and ponds. They destabilize river and pond
banks and destroy habitat for native fish and waterfowl. The effect on the water quality is dramatic as they disturb the
bottom of streams and ponds as they grub through bottom sediments and uproot plants, significantly increasing water
turbidity.
The koi is an opportunistic feeder, eating insects, juvenile fish of other species, a diverse range of plants and
organic matter. Once introduced they can quickly become the dominant fish in water bodies.
Legal designation
• Unwanted organism
• Noxious species
Impact of pest fish
Many people are unaware of the damage done to our waterways by pest fish. Unfortunately some types of introduced fish
have spread into the wild, become pests and are threatening New Zealand’s freshwater species and environments by:
• Stirring up sediment and making the water murky
• Increasing nutrient levels and algal concentrations
• Contributing to erosion
• Feeding on and removing aquatic plants
• Preying on invertebrates, native fish and their eggs
• Competing with native species
Even if we were to ban farming totally we would still have a problem with water quality from the effects of the invasive
pest fish species.
So in relation to the Ecosystem Health as set out in the plan change document, surely Koi Carp must be addressed as they
have a huge effect on the rivers from the damage they do. Along with Catfish they are one of the most rapidly
multiplying invasive pests that have been released into the New Zealand environment.
Koi Carp and catfish are now common in our waterways but have been largely ignored with the focus for water quality
improvement being almost totally on the effects from agriculture.
The Koi Carp is now rapidly becoming one of the worst invasive pests in New Zealand and as such and taking into account
their geographic spread, they are a problem where the solution should be funded by central government and not by the
general ratepayers in any particular region.
They are now a national problem and require a national solution and appropriate funding from central government to allow
control measures to be implemented across the whole country.
What we're actually dealing with is the multiple impacts that humans are having on the waterways and if we really want
to restore these water bodies to what we want them to be then we need to have fit for purpose legislation that still
allows for all parts of society both Urban and Rural, to provide for their social, economic, and cultural well-being and
for their health and safety as stipulated in the Resource management Act 1991.
Going forward
The region, in fact New Zealand as a whole has to have a discussion and decide, what is the standard that is required
across the whole country and then enact that standard nationally, rather than the current situation where we have
differing standards across all of the regions in New Zealand.
If as part of that discussion it is desired that we take actions that impact on the ability of rural land users and
communities to carry out activities that are currently legal then we must as a nation, in the interests of natural
justice, be prepared to fairly compensate those land users and communities for the reduction/removal of those current
legal rights.
In saying that then we must also provide the same certainty of fair compensation to urban land users and communities
that face a similar reduction/removal of any existing legal rights.
This discussion around the national standards must include any requirements in relation to Climate Change, Greenhouse
gas Emissions reductions, ETS and the proposed Zero Carbon Bill as opposed to the current ridiculous situation where,
under regulation such as PC1 proposed by WRC, this is inconsistent with Government’s climate change goals.
To be undertaking legislative change at a regional level that is going to end up with requirements that are the reverse
of New Zealand’s obligations at a national; and international level would be nonsensical to say the least.
Specifically, the grand parenting of diffuse nitrate discharge rights serves to discourage research and innovation into
alternative / lower GHG emission farming methods. Grand parenting emissions rights based on past practice serves to
discourage innovation and slow the adoption of alternative, less damaging farming practices.
Surely we can achieve more and better outcomes by taking the time now to ensure that all of our obligations under any
climate change accords are accounted for whilst still achieving the desired improvements in water quality under local
government legislation (i.e. PC1).
To have any chance of success in addressing the desired improvements in water quality then we “MUST” put in place strategies to deal with the invasive pest fish species such as Koi Carp and Catfish and have these
included in PC1.
Failure to address the pest fish issues will result in absolute failure of the ability to achieve the requirements of
the Vision & Strategy, relating to Swimmability and Food gathering.
The water will be too sediment laden for swimming and there will be no native flora or fauna left for food gathering
after the Koi Carp have finished feeding.
Andy Loader
Co-Chairman P.L.U.G.
(Primary land Users Group)