An urgent need for action as native freshwater mussels populations at Lake Rototoa, near Auckland

Research shows only 15-percent of the lake's kakahi remain, with pests and pollution primary causes in the decline.

The species is crucial for sustaining water quality and supporting other marine life.

Auckland Council Senior Biosecurity Advisor Belinda Studholme says sterilised gear is key to stopping the spread of ecological threats.

She says unclean equipment can move invasive organisms between ecosystems, with it just taking a fragment of a weed.