Case study - Responding to a new marine pest
In 2007 large ascidians (Pyura doppelgangera) were found covering some rocks in the Far North. By May 2009 these ascidians were covering a much wider area than the original detection site. Using the Biosecurity Response Knowledge Base, MPI undertook an assessment of the potential impacts to New Zealand’s core values of the invasion. This indicated medium-level risks to the economy, the environment, social and cultural well-being and Māori values. The values at risk were assessed as outlined in the figure below.
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Economic |
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Environmental |
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Social and cultural well-being |
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Māori values |
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A survey was undertaken to determine the extent of the infestation. The survey showed Pyura was present at many locations on the west and eastern coasts of the Far North, suggesting the species had been present for some time prior to the initial detection. MPI decided that eradication could not be achieved, given the widespread nature of the incursion. However, local iwi and stakeholders were very concerned about the marine pest and MPI decided to trial the feasibility of local elimination at three sites in the Far North beginning in 2010.
The results of the trial suggested that periodic clearances of the ascidian could suppress the populations at specific sites. The field team was comprised of personnel from iwi (who received training in marine biosecurity and field research methods, MPI and Northland Regional Council, and DOC contributed resources. The Te Hiku o te Ika Fisheries Forum, comprising representatives of mandated iwi organisations, participated throughout the trial. The Forum developed a marine biosecurity strategy for the Far North and is currently working with the Northland Regional Council to develop a long-term management plan for this marine pest.
Last updated at 1:26PM on February 6, 2018