Kanakana harvest mātauranga: Potential tools to monitor population trends on the Waikawa River, Southland/Murihiku?

About this research

The population of kanakana (piharau, lamprey) is poorly understood and believed to be declining. In Murihiku concern for this taonga species led to this research in the Waikawa River.

This Ngā Pae o te Māramatanga project focused on developing a method that is not only effective as an index of kanakana population abundance, but also has tangible links to the practice of mahinga kai, traditional Māori harvesting practices. This will enable the kaitiaki to conduct the monitoring, interpret the results and integrate their mātauranga into the management of this resource. It will also help protect this species hopefully for generations to come.

Māngai Piri or Niagara Falls and the upstream Top Falls are sites where the long-held tradition of kanakana harvest continues on the Waikawa River. Māngai Piri is adjacent to a nohoanga, a traditional seasonal mahinga kai gathering area. Here the fish are harvested at night, by hand, off the rocks on their way up the falls at night.

Led by Principal Investigator Dr Jane Kitson, the project compared the use of the Dual-Frequency Identification Sonar (DIDSON), a modern method used to determine population abundance in other fisheries, to observers conducting visual counts, a method akin to traditional harvest methods.

The results from the two showed similar numbers, however observer fatigue limited the visual counts by two days, which suggests this method is not sustainable over the long term. So the researchers indentified other possible monitoring tools in line with traditional methods, such as using traps made of brush and bracken that would capture kanakana and enable counts during the day.

Further research into how effective these other traditional methods are as indices of abundance is to take place during a number of seasons.

Outputs
This study has been used in the Ministry for Primary Industries (MPI) kanakana response and this year customary harvesters have been the main monitors/collectors of samples for the response to help determine what is affecting our taonga fishery.