Don’t spread unwanted freshwater pests this hunting season

With duck shooting season starting on Saturday 5 May, Taranaki hunters are being reminded it’s vital to clean their equipment between waterways to avoid the spread of unwanted freshwater pests including the invasive alga didymo. The reminder comes from the Taranaki Regional Council and the Ministry for Primary Industries. “Unwanted freshwater pests such as didymo, lake snow, hornwort and oxygen weed pose a serious threat to our rivers, streams and lakes,” says the Council’s Environment Services Manager, Steve Ellis. 

“Once in a waterway, they can disperse rapidly and destroy the environmental, recreational and aesthetic values of our waterways. So we are asking hunters moving between waterways to ‘Check, Clean, Dry’ any equipment that has come into contact with river or lake water – particularly boots,” he says.

“Some freshwater pests, like didymo and lake snow, are microscopic and can be spread by a single drop of water. Even if you can’t see the danger, you could be spreading it.”

Mr Ellis says before leaving a waterway, people should check items and leave any weed or debris they find at the waterway.

“All items should then be cleaned for at least one minute with a 5% solution of biodegradable dishwashing solution. That’s about one tablespoon of detergent per 250ml,” he says. “Water-absorbent materials such as boots require longer soaking times to allow thorough saturation.

“Drying will kill didymo, but even slightly moist items can harbour didymo and other microscopic pests for months. To ensure didymo cells are dead by drying, the item must be completely dry to the touch, inside and out, then left dry for at least another 48 hours before use,” says Mr Ellis.

“Following these simple procedures will help slow freshwater pests like didymo from spreading throughout New Zealand waterways. It’s everyone’s responsibility to try to preserve the environmental integrity of our waterways for future generations.

“Just remember to Check Clean Dry when moving from one waterway to another, anywhere in New Zealand.”

For more information about didymo and freshwater pests visit