First Didymo survey negative, caution needed

DATE 7 October 2005

First Didymo survey results negative but caution still needed.

Surveys of the Northern third of the South Island have not found any more rivers affected by the invasive Didymo alga, Biosecurity New Zealand announced today.

Additionally, several samples from other rivers in the central South Island, the Waitaki, Tekapo, and Ohau Rivers, and the Travers River in the Buller catchment, which had been reported in the media as possibly being Didymo, have proved to be negative. Formal surveying of these areas will take place over the next few weeks.

The only place in the Buller where Didymo has been confirmed was the original find in the main stem just downstream from Lake Rotoiti (Nelson). Survey results from elsewhere in the Buller catchment were negative.

Biosecurity New Zealand chief technical officer Peter Thomson said that while the negative results from the 110 tested sites were great news, cleaning precautions were still necessary for people using equipment in more than one river, and would remain that way for the foreseeable future.

“New Zealand is still clean and green, but New Zealanders must not take this for granted. The way of life for freshwater users needs to change. It is the personal responsibility of every New Zealander using freshwaters to take the appropriate precautions after using any river or lake to avoid spreading Didymo.

“While we have confidence in our results caution is still necessary. We are dealing with a microscopic organism in millions of litres of water over hundreds of kilometres of river. River users can spread Didymo very easily, and the risk won’t always be apparent. The message about the dangers of aquatic pests is not a new one, and Didymo certainly highlights the seriousness of the issue,” Mr Thomson said.

Meanwhile, surveys in the North Island got underway in the Turangi, Taupo and Tongariro area today, with helicopters used to access some areas. Surveys elsewhere in the North Island and in the southern third of the South Island will continue next week.

Biosecurity New Zealand is awaiting a report from the organisers of the jetboat marathon in Southland on the measures jet boaters propose to take to minimise the risk of spreading Didymo and will comment on it once it has been received and assessed.

“It’s been a busy time for many staff, and we appreciate the efforts of those organisations who have helped us get on with the job,” Mr Thomson said.

Meetings with stakeholders continue, and the efforts of all groups to work proactively with Biosecurity New Zealand while the present situation is being dealt with is much appreciated. A public meeting held in Murchison last night has been a positive and useful experience. Similar meetings are planned for other locations in survey areas during the next few weeks.

To date the only rivers to have tested positive for Didymo are the Mararoa, upper and lower Waiau, Oreti, upper Clutha, Hawea and the Buller.

ENDS

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