Didymo News

The words no one wants to hear ‘didymo has been confirmed in the North Island’ greeted representatives from MAF Biosecurity New Zealand, DOC and other stakeholders brought together to participate in a MAF simulation exercise for didymo (Didymo spheniagerminata) in Taupo at the end of May.

The latest findings from MAF Biosecurity New Zealand's Didymosphenia geminata (didymo) science programme were presented to the Didymo Technical Advisory Group and Long-Term Management partners at a seminar held in Wellington today.

Didymo has been detected in Queenstown Bay in Lake Wakatipu, Biosecurity New Zealand and the Queenstown Lakes District Council announced in early February.

The organism has previously been detected in other parts of the lake and has been known to bloom on the fringes of lakes where there is sufficient wave action. Didymo has been found in other lakes fed by affected rivers. Four affected rivers flow into Lake Wakatipu. Its main impact is expected to be visual only, though there is obviously a risk of spread.

The Department of Conservation Taupo Fishery Area has an education programme called “Taupo for Tomorrow education”. Educator Thea Depetris has designed a didymo teacher information resource

Now that most New Zealanders are back to work the main risk is posed by the large numbers of independent travellers visiting the country. Targeting these travellers has been a challenge.

Employing contract workers at the Wellington ferry terminal has enabled us to get the message out to travellers before they get to the South Island. It has also produced some alarming statistics:

• More than 50% of travellers currently crossing to the South island are from overseas
• Of these, most have not yet heard of Didymo

Felt soled waders are a high risk vector for spreading Didymo. We are currently producing an information sheet and poster to ensure all anglers know how to treat their boots.

• We recommend that felt soled boots are not used by anglers fishing more than one river who are unable to guarantee to decontaminate the boots after every trip.
• Freezing boots until solid is widely accepted as the most viable method for decontamination

The spread of Didymo through the South Island increases the chance of a North Island incursion and puts yet more pressure on our operations. The current priorities are:

• Implementing more effective boarder control. We are currently working with BNZ to extend the coverage at the Cook Strait Ferry. It is also clear that a fresh approach is required to get the message to travellers using our domestic airports
• Developing a monitoring programme to maintain regular surveillance at critical North Island sites