Protecting a regional treasure

We have stepped in to help protect the critically-endangered Canterbury mudfish / kōwaro. Lack of fencing of livestock from streams, riverside willows and other weeds, few native plantings, sediment and nutrient run-off into streams are major threats to its conservation.

The Waianiwaniwa valley in inland Canterbury is a major habitat for the endemic kōwaro. The streams here become disconnected from rivers in the lower Selwyn catchment due to seasonal drying of the streams as they enter the Canterbury plains, creating an environment free of predator fish species such as eel (tuna). This catchment however, like much of Canterbury, is dedicated to rural land use and is relatively unprotected for the kōwaro.

On gaining access in May 2020 to a purchased 31-hectare block of rural land, we committed to fencing 1,100 metres of the Bush Gully Stream from livestock. We are also spraying weeds and planting riparian native species along this stream. This is part of a programme to protect and enhance kōwaro habitat in the Bush Gully Stream which runs to the north of the Canterbury mine and later joins the Waianiwaniwa River.

Other actions are to remove two stands of crack willow as part of a wetland restoration project. We manage run-off into freshwater from the mine, making improvements to fish passage. The intent is to covenant 20 metres on either side of the mid-point of Bush Gully Stream for 1,100 metres, over an area totalling 44,000 m2 or 4.4 hectares.

Improving the science

We supported a survey of kōwaro populations in the Bush Gully Stream via a University of Canterbury master’s thesis, and more widely, the Waianiwaniwa and Hororata catchments. This work builds on other aquatic surveys on kōwaro carried out in Bush Gully Stream since 2006.

A further issue is uncontrolled drainages into the Bush Gully Stream from historical underground mines dating from the 1900–1970s. We are analysing water quality and quantity in these flows to understand how these drainages can be managed to improve stream water quality.

A holistic issue

Nature conservation can rarely be done in isolation to be effective. This is especially true of the kōwaro and its stream habitat, almost all of which is degraded. This is a call for action on landowners, farmers and foresters, mine and quarry operators, government, iwi and local communities. We are proud to be playing our part in this kaupapa or cause.

We are proud to be playing our part in this kaupapa to protect the kōwaro.