Didymo control efforts strengthened – but personal responsibility the key
Biosecurity New Zealand has strengthened Didymo control efforts with a South Island-wide Controlled Area, enhanced
public awareness activity and a $1 million summer research programme into potential control tools, but personal
responsibility remains the key tool in reducing its spread.
Biosecurity New Zealand Director Post-clearance Peter Thomson says the revised strategy still relies on all freshwater
users doing the right thing: “Nothing we can do cancels the need to clean between waterways anywhere in New Zealand. It
applies to everyone, everywhere, everytime.”
The new Controlled Area replaces all existing Didymo Controlled Areas and comes into effect tomorrow (Friday 9 December
2005), making it a legal requirement to clean items that have been in contact with lakes and rivers when leaving the
South Island and before entering another waterway. Spot checks at entry and exit points will be conducted, and the need
to clean with Biosecurity New Zealand-approved “soak-scrub”cleaning methods promoted.
“Extending the Controlled Area to the whole of the South Island acknowledges how big this issue is. The idea is to get
ahead, rather than play catch up. To restrict access locally every time a new river is found to be affected is not a
sustainable option. Didymo could survive in more than half of New Zealand’s waterways, but it is a risk that can be
managed if people are responsible.”
Mr Thomson says the strategy acknowledged several factors – that no known eradication method existed, that no river
could be guaranteed “Didymo free,” the inability to police every river activity, and that responses had to be balanced
and mindful of other impacts, including people’s livelihoods.
“Public awareness is our main tool and that campaign is being strengthened. Didymo is still an unwanted organism, and it
is an offence to knowingly spread it. Breaching the Controlled Area could also result in severe penalties,” Mr Thomson
says.
“Extensive efforts to promote the need to clean equipment will use a “Check, Clean, Dry” slogan. Regular river users
such as fishing licence holders, fishing guides, kayakers, rafters and jetboaters have already recognised the need with
codes of practice. The rest of the country needs to follow their lead. A $1 million summer research programme will
investigate potential control tools.”
Mr Thomson says Biosecurity New Zealand has been aware of the calls for action made by various organisations and was
satisfied a constructive and cohesive way forward was now in place.
“It’s been a complex issue to work through, with many differing views. We have been grateful for the robust input from
stakeholders which has shaped our management response”.
“Reducing the spread of Didymo will be a team effort, involving all river users in New Zealand. Biosecurity New Zealand
will continue to work with stakeholders and the tools they have to strengthen our effort to slow the spread of this
pest. We anticipate some organisations will put in place extra measures to protect high value sites based on local
knowledge of their areas and we support that,” Mr Thomson says. Media contact: Phil Barclay, Senior Communications
Adviser, 027 229 9145. Notes to reporters:
In making management decisions, Biosecurity New Zealand has to be mindful of several points:
While Didymo has been identified in eight rivers, Biosecurity New Zealand cannot guarantee that it will not be found in
others. Biosecurity New Zealand is unlikely to ever be in a position to guarantee that a given river is free of Didymo.
All New Zealand waterways should be considered at risk of being or becoming affected. Enforcement of every single river
activity on every affected river is not practical. No eradication methods are currently available. Public awareness and
personal responsibility remain the most sustainable tools to reduce the spread of Didymo.
Penalties under the Biosecurity Act 1993 for knowingly spreading Didymo or breaching the Controlled Area conditions are
a fine of up to $100,000 and/or up to five years’ in prison.
Biosecurity New Zealand will be erecting “Check, Clean, Dry” signs at known affected rivers and elsewhere, and
Controlled Area signs at main access points to the South Island, including airports and Cook Strait ferry terminals.
River patrols will also be conducted.
Biosecurity New Zealand-approved cleaning methods for the South Island Controlled Area are: Check: Before leaving the
river, remove all obvious clumps of algae and look for hidden clumps. Leave them at the affected site. If you find any
later, do not wash them down drains. Treat them with the approved cleaning methods below, dry them and put them in a
rubbish bin. Clean: Soak and scrub all items for at least one minute in either, hot (60°C) water, a two percent solution
of household bleach or a five percent solution of salt, nappy cleaner, antiseptic hand cleaner or dishwashing detergent.
A two percent solution is 200 ml, a five percent solution is 500 ml (two large cups), with water added to make 10
litres. Dry: If the above cleaning is not practical, after the item is completely dry to touch, wait an additional 48
hours before contact or use in any other waterway. Use of alternative methods would mean the user was in breach of the
Controlled Area.