Start of fishing season highlights risk to lakes

Friday 30 September 2005

The spread of an invasive alga into new areas of the South Island has highlighted yet again the need for all boaties to clean their boats carefully after using them.

The microscopic alga, called Didymosphenia geminata, looks slimy but feels like cotton wool and can be spread in a single drop of water. It was identified in Southland in October last year in a Southern Hemisphere first. Now, it has turned up further north in the West Coast’s Buller River.

For the past few years, Environment Bay of Plenty and the Department of Conservation have strongly promoted the need for boaties to clean their boats after use. Environment Bay of Plenty’s pest animal coordinator David Moore says unwashed boats can transfer new aquatic weeds or pest fish into Bay of Plenty waterways. This is of particular concern to the vulnerable Rotorua lakes. Once established, pest plants and fish can degrade water quality, become a nuisance to lake users, and escalate the decline in native aquatic plant communities, he explains.

Mr Moore says BioSecurity New Zealand is extremely concerned that the alga has spread in spite of all efforts, including setting control zones. “They are very worried - and so are we. It shows just how careful boaties have to be if they want to keep the Bay of Plenty’s lakes and waterways safe.”

The trout fishing season, which opens this weekend (October 1), is always a risky time for the Rotorua lakes. “We have boaties coming from other parts of the North Island who may not realise the importance of cleaning their boats down,” he says. “They may not realise that all it takes is a single fragment of weed – or in the case of this alga, a single drop of water.”

“Not all lakes have the same weed so it’s important to check your boat between outings on different lakes and waterways,” says Department of Conservation spokesperson Sarah Crump. Skippers must inspect their boats, including propellers anchor chains and trailers, when leaving a lake. They need to remove all weeds, flush out jet units, and wash their boat down if necessary.

ENDS

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