Our approach to monitoring addresses many elements of the 2015 Freshwater Mussel Conservation Strategy NZ, including developing monitoring methods, being highly collaborative and protecting quality mussel habitat. 

Key to the project are relationships that have been building over time, such as with mana whenua with interests in the area; Te Kawerau a Maki and Ngāti Whatua o Kaipara, represented by Nga Maunga Whakahii o Kaipara Ngahere. The work within Woodhill Forest and the northern section of Riverhead Forest is of particular significance to Ngā Maunga Whakahii o Kaipara, and the recognition of their role as kaitiaki and landowners. The inclusion of kaitaki in the project's survey efforts acknowledges the importance of mātaraunga Māori in shaping environmental conservation practices. 

We have undertaken surveys in streams in the Kāipatiki catchment and the Riverhead/ Coatesville catchment. Working with subject matter experts, we undertook a programme of designing and testing an eDNA protocol for small, slow-moving streams to assess the presence and absence of E menziesii.  

In 2024, we surveyed streams on the Kaipara Harbour side of Riverhead Forest, receiving results from the eDNA testing that suggested one of these latter streams also held individuals of E aucklandica. Up until this discovery, there was little information available to suggest that this rare species was in the Kaipara catchment at all. 

During our exploration of the stream and the subsequent discovery of not only large individuals, smaller post juvenile individuals and also recent post mortem evidence of at least one small juvenile, we became aware through communication with kākahi experts in New Zealand at DOC, NIWA, Auckland Council Healthy Waters and Te Papa, that juveniles were extremely hard to find and that as a result of an apparent failure to breed, there was great concern that in the Auckland Region at least, this rare species could be extinct within a very few years. 

Kākahi population health can be quickly assessed by locating younger juvenile bivalves, between 1.5 and 4cm in length, as well as in some circumstances, individuals less than 10mm in length. It is not uncommon to find numbers of larger adults at a site, some up to 100 mm long, but they can represent stagnating populations or remnants, living for up to fifty years but without successfully generating young.  

By locating healthy functioning populations of both species and tying these results in with up-to-date knowledge of native fish presence in our local streams, we can:

• Identify areas to actively protect kākahi from predators.
• Maintain free from blockages to fish passage.

This work will assist the continuity of these important taonga species for years to come.