Mahinga kai - what species interests you?

Note: Kaitiaki Tools were developed to assist people involved in the resource consent process and focusses on the potential impact of land-use change or point source discharges on freshwater mahinga kai. This project was completed in 2011. Some information may be outdated.

In Kaitiaki Tools the term mahinga kai generally refers to indigenous freshwater species that have traditionally been used as food, tools, or other resources.

Aotearoa's freshwater fish fauna is unique and diverse. However, our native fish are not protected under the Wildlife Act (1953), except on conservation land. Land use and developments that damage and pollute species habitats are the greatest threat to their survival.

Some important factors need to be taken into consideration when assessing the impacts of a particular land use activity or point source discharge on mahinga kai species. Some examples are:

• Mahinga kai species will be able to adapt to a gradual change in water quality to a point; however, they are less likely to cope with extreme and sudden changes in water quality.
• The rate of mahinga kai metabolism depends on water temperature. This means that any increases in water temperature may also increase the intensity or magnitude of any effect on mahinga kai.
• The age and size of mahinga kai species generally has an effect on tolerance limits, i.e., small juveniles have a lower tolerance than adults.
• Interactions between various substances and contaminants can change the toxicity of individual substances.
• The toxic effect of various substances depends on the acidity (pH) and the concentration of dissolved oxygen in the water.
• Some substances can slowly accumulate in the tissues of mahinga kai species; any effect may not be immediately apparent but increase over time.

Find out more about temperature changes

Find out more about chemical contamination