As experimental aquaculture involves new types of marine farming, it is difficult to predict the environmental effects with a high level of certainty.
As fish farming is likely to be the next form of aquaculture promoted, we are paying particular attention to the potential ecological effects of caged fish farming and looking at experiences overseas and in the South Island (salmon farming).
Potential effects can be addressed at both the plan change and the resource consent stage. Determining the right mixture of controls at these stages will be an important part of the plan change process.
Potential ecological effects
The ecological impacts of cage fish farming include localised impacts on currents and water flow, impacts of wastes arising from the operation (nutrients and chemicals) and impacts associated with escaped farmed fish interbreeding or interacting with local fish populations, as well as wider impacts on birds and mammals.
Fish farming operations in a number of countries have shown effects arising from wastes vary from site to site. In general significant effects are quite localised. Only where the density of aquaculture operations is very high have large scale significant effects been documented. Less is known about wider ecosystem effects such as the genetic impacts of escaped fish on wild fish populations, and effects on mammals and seabirds.
The management of fish farms has improved with experience, which means that techniques are now available to help avoid or mitigate many of the ecological impacts.
The current state of knowledge of the ecological effects of cage fish farms is being reviewed by the Cawthron Institute for the Ministry of Fisheries. This review draws on both international and New Zealand experience and is available on the Ministry of Fisheries website.
Other potential effects
Other impacts that could arise are the degradation of natural character, landscape and amenity values, impacts on cultural values and the relationship of Maori with their ancestral waters, restrictions on public access, noise, impacts on navigation safety and conflict with recreational uses.
To some extent these can be addressed by limiting new forms of aquaculture to areas that are already being farmed but these potential impacts may also need to be considered on a case by case basis if new types of structures are being used.
Impact studies
To expand on our understanding of the potential effects of fish farming, Environment Waikato has commissioned a range of technical studies. These will be posted on our website as they are completed. Click on the links below to view the reports completed so far.