Kio Carp & Water Quality
Koi Carp Facts:
Fact: Koi Carp are designated as an unwanted organism and a noxious species.
Fact: Koi Carp have no natural predators in New Zealand waters.
Fact: Koi Carp are very successful breeders in New Zealand with each adult female producing 100,000 eggs per kilo of body weight.
Fact: Koi carp cause habitat loss for plants, native fish, invertebrates and waterfowl.
Fact: 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 spawn11 more than once). Koi carp spawn throughout the summer. As they gather for spawning12 or feeding in the shallow margins of the river, koi biomass can reach 4000 kg/ha.
Fact: 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.
Fact: Koi carp cause habitat loss for plants, native fish, invertebrates and waterfowl.
Fact: They feed like a vacuum cleaner, sucking up everything and blowing out what isn’t wanted and they burrow away at the banks causing erosion7 as well, so they contribute to poor water quality in a number of ways. Aquatic plants are dislodged in the process and are unlikely to re-establish.
Fact: 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 and they significantly increase water turbidity. Once introduced they quickly become the dominant fish in water bodies.
Fact: Koi carp are widespread in Auckland and Waikato. (The population has exploded, and they now make up 80% of the total biomass3 in the lower Waikato/Waipa river catchment. It has been estimated that there are approximately 500,000 tonnes of Koi Carp in the lower Waikato/Waipa Catchment).
Fact: Koi carp prefer still waters, spreading from rivers into lakes, streams or backwaters in rivers. They are highly tolerant of poor water quality – surviving well in degraded water and contributing to the decline.
Fact: 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 spawn11 more than once). Koi carp spawn throughout the summer. As they gather for spawning12 or feeding in the shallow margins of the river, koi biomass can reach 4000 kg/ha.
Fact: Koi greatly increase the turbidity of the water because they are constantly stirring up the substrate. This makes waterways unattractive, reduces the abundance of aquatic plants, and can render the water unsuitable for swimming or drinking, even by livestock.
Water Quality & Impacts of Koi Carp:
Many people are unaware of the damage done to our waterways by pest fish. Unfortunately some types of introduced fish such as Koi Carp have spread into the wild, become pests and are threatening New Zealand’s freshwater species and environments by:
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 surely Koi Carp must be addressed as they have a huge effect on the rivers from the damage they do. They are one of the most rapidly multiplying invasive pests that have been released into the New Zealand environment.
Koi Carp are now common in the Waikato/Waipa 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 national problem and require a national solution 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.
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.
Failure to address the pest fish issues will result in absolute failure of the ability to achieve the requirements of the NPS on Fresh Water Quality.
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.
P.L.U.G. (Primary Land Users Group) has been in discussions with and made many submissions to the Waikato Regional Council, the Waikato River Authority and also to the hearings committee for the PC1 process, in regard to the Koi Carp issues and Water Quality.
We firmly believe that if the issue of pest fishes (mainly Koi Carp & Gambusia) are not dealt with then all of the measures that have been put in place under the new Freshwater Management Standards will not achieve any of the desired results in relation to water quality.
In the Waikato Region alone, analysis of the new rules has been undertaken by the Local Government organisation and this has found that the new rules will result in approximately 68% of Sheep and Beef farmers and 13% of Dairy farmers will go out of the industry.
Yet unless we address the pest fishes issue then this sacrifice of our farming industry will mean nothing as we still will not achieve the desired result in relation to water quality due to the adverse effects from Koi Carp, in the Waikato region.
We believe that part of the reason is that the authorities don’t know how they are going to deal with the issue of eradicating Koi Carp or how it can be funded.
They can put the onus onto the farming community to effect water quality improvement and they do not have to fund it or take direct actions to implement the new rules. Just regulate the farmers into taking action and funding all of the implementation. It doesn’t seem to matter initially whether the new rules will actually deliver the desired result as long as they are seen to be doing something.
Wonder who will take responsibility when it is realised that most of the pain and suffering from the rural sector has been in vain as the Koi Carp are still there breeding and expanding their numbers at a great rate and further exacerbating the water quality degradation problems.
Koi Carp also contribute greatly to the reduction in indigenous biodiversity through both predation on native species of flora and fauna and also the loss of habitat through erosion of waterway margins & degradation of water quality from their feeding methods.
Andy Loader
Co-Chairman P.L.U.G.