Didymo Stakeholder Update - 31 March 2006

Didymo work continues

Whilst the weather gets colder, water levels (hopefully) get higher and freshwater user numbers reduce -Didymo work is still continuing.

Economic Impact Assessment

The Economic impact assessment has recently been added to the Biosecurity website www.biosecurity.govt.nz/didymo under the reports section.

This assessment estimates potential present value impacts of Didymo on New Zealand’s commercial fresh water fisheries; municipal, industrial and agricultural water intakes; community, municipal and domestic drinking water; local recreation value; international and domestic tourism expenditure; local and national existence values; and existence values associated with extinction of native species, over the eight years 2004/05 to 2011/12, to total:

• $57.798 million under the low impact scenario;
• $167.233 million under the medium impact scenario; and
• $285.132 million under the high impact scenario.

Total impacts are greatest in the North Island and central South Island. Although the lower South Island has the largest amount of highest risk environment for survival of Didymo and is where impacts occur earliest, the central South Island and North Island have substantially larger human populations to suffer reduced recreation and existence values.

Controlled Area

Movement controls have been issued for the Monowai River and Lake while Didymo control trails are being undertaken in the area. The control trials will identify and test control methods to assess effectiveness as a Didymo toxin and as a disrupter of stalk formation. Impacts on non-target biota will also be investigated. Feasibility for successful delivery in affected waterways, risks which could affect success, duration required for effective control, and cost to implement over large scales will be evaluated. For more information on scientific trails being conducted and final results please visit www.biosecurity.govt.nz/didymo.
A science open day is planned at the Monowai on 11 April for local body councillors, media and some scientists to view the trails in action.

Delimiting Survey

A National delimiting survey will start in April, meanwhile Didymo has been confirmed in the Aparima River in Southland.

Meetings

A meeting with irrigators is also planned for April 12 in Christchurch to look at issues irrigators will face with didymo infestations.

Biosecurity staff is delighted with the proactive response of the Taupo community to Didymo. After a well attended meeting last week in Taupo, DOC and Fish and Game are leading an initiative to increase the effectiveness of the Check Clean Dry message in their area.

Public Awareness Research

Research has also been completed on awareness and behaviours of freshwater river users.
Results indicate that :

• 57% of the New Zealand population participates in freshwater activities
• Freshwater users aware of Didymo:
  • 75% of all surveyed
  • 90% of those surveyed in the South Island
• Freshwater users aware of the phrase 'check, clean, dry' (launched in November 2005):
  • 53% of all surveyed
  • 60% of those surveyed in the South Island
• Freshwaters users undertaking different actions since hearing about Didymo:
  • 29% of all surveyed
  • 36% of those surveyed in the South Island

Again we would like to thank everyone for their help and assistance in slowing the spread of didymo.