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Finding the elusive freshwater mussel

Horizons Regional Council wants to hear from anyone who has seen kakahi (freshwater mussels) in the Region’s rivers, streams or lakes.

Horizons senior environmental scientist for water quality Logan Brown says surveys on kakahi are important as they’re an exceptional indicator of water quality.

“Horizons studies a number of identified sites but it would assist us greatly if we could tap into the community’s knowledge of areas where they can be found or have been found in the past.”

“Studying kakahi teaches us about the health of the water body as they filter their food out of the water and effectively provide a record of the quality of that water over their lifespan.

Because kakahi are capable of living anywhere between 30 to 50 years, this record can be substantial,” says Mr Brown.

Kakahi can be found in all parts of the Region and inhabit sheltered parts of lakes and rivers where the bed is sandy as they burrow into the sediment. They typically measure between 60mm and 80mm and juveniles can be anything under 30mm. 

“We’re especially interested in the presence of juvenile kakahi as they will tell us whether the population is sustaining itself or if it’s in decline,” says Mr Brown.

One way of identifying a spot where kakahi may lie is by looking for trails in the riverbed or lakebed.

“Freshwater mussels are different from saltwater mussels in that they roam free on the beds of rivers or lakes instead of clinging to rocks or other surfaces like saltwater mussels and thus they leave trails wherever they go,” says Mr Brown.

If you have any information regarding the whereabouts of kakahi please freephone Horizons on 0508 800 800 and ask for the science team.