Wairarapa Moana Kākahi Sampled

Twenty volunteer Citizen Scientists took to the water alongside Greater Wellington Regional Council staff to collect, record and replace kākahi (native freshwater mussel) last weekend.

"It was a perfect day at the lake and the teams worked across designated zones recording data. The mussels were collected quickly; there were good numbers in this area although volume does not necessarily indicate a 'healthy' population, the size and condition of the samples need to be analysed and this will provide us with a clearer picture," says Toni de Lautour, GWRC Biodiversity Officer.

This is the second monitoring event of this long-term programme to understand the health of the kākahi population at Lake Wairarapa, an essential part of a long-term plan towards restoring our wetland treasure. The status and health of the kākahi (native freshwater mussel) population helps us understand the health of the wider ecosystem and can measure the progress of restoration activities. The monitoring takes place on an annual basis and the information will be collated into a new national database as well as support the decision making of Wairarapa Moana partners.

There are three species of kākahi in New Zealand and two of these are found in Lake Wairarapa. They can live between 30 years and 50 years and grow to between 60 and 80 mm, although there are records of much larger specimens. Kākahi are found in sheltered parts of rivers and streams where the bed is sandy or silty, and in lakes. They burrow into the sediment and are hugely efficient at filtering sediment out of the water. In the past, large beds of kākahi probably helped to maintain the clarity and quality of our waterways.

There are records of kākahi found in the Kopuaranga and Whangaehu and the lower reaches of the Ruamahanga River, although in much lower numbers than they once were. They appear to be more plentiful in Lake Wairarapa. Kākahi don't usually live in heavy gravel rivers, such as the Waiohine and Waingawa, as these rivers lack the stable and sheltered spots kākahi favour.

Enhancing the ecology and the recreational and cultural opportunities around Lakes Wairarapa and Onoke is managed through a long-term collaboration, the Wairarapa Moana Wetlands project, a joint commitment by: South Wairarapa District Council, Ngāti Kahungunu ki Wairarapa, Rangitāne o Wairarapa and Papawai and Kohunui marae, Department of Conservation and Greater Wellington Regional Council.

ENDS

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