Applying the right tools to restore kōura to lakes and streams

The tools available for restoring kōura to lakes and streams depend on what is causing kōura to decline.

A decision support system (DSS) for the kōura found in New Zealand streams shows which of the restoration options below is likely to help restore the species in your stream. 

Generalised decision support system (DSS) for identifying causes of low kōura abundance in New Zealand waterways. [NIWA]

Find out more about restoration options for the problems in your stream:

Kōura and other aquatic animals thrive in a variety of different habitats. See restoring physical stream habitat.

The known water quality preferences and tolerances (temperature, pH, oxygen, ammonia and turbidity) for common native fish and kōura are shown in the Known water quality preferences for common native fish table. See also improving water quality.

Pest species of fish and plants will need to be controlled or eradicated if they are threatening the success of your restoration project. See controlling pest fish.

Cover habitat for kōura and fish can be riparian (i.e. over the stream) or instream/inlake (e.g. wood debris or boulders). See restoring riparian and instream cover.

Changes to water flow regimes can affect kōura in several ways. See restoring flow.

If you suspect overfishing is reducing kōura numbers, contact DOC or iwi authorities. See also reducing overfishing.

If the low abundance of kōura in your waterway is not related to a reduction in habitat, water quality, flow, it might be due to an event that has decimated the kōura populations such as a chemical spill or lake-turnover i.e. rapid mixing of lake bottom waters high in toxic ammonia and sulphide with the rest of the lake when thermal stratification breaks down in autumn. Consult a qualified and experienced freshwater ecologist and the Department of Conservation (see this permission form) before attempting any restocking kōura initiatives.