Recommendations for management of Auckland region's freshwater pests

Paul D Champion, Mary de Winton, National Institute of Water and Atmospheric Research Ltd NIWA
Auckland Regional Council
Publication date:

Auckland Regional Council currently manages a range of aquatic pests under their Regional Pest Management Strategy. “Total Control Plants” under this strategy include fringed water lily (Nymphoides peltata) and purple loosestrife (Lythrum salicaria) for which control of all known sites has led to the eradication of most populations of these high-risk weeds. However, other species more widespread in their distribution that are known as “Surveillance Plants” under the strategy are not currently managed apart from enforcing their restriction of sale, propagation and distribution and undertaking localised control (e.g., egeria - Egeria densa control on Great Barrier Island).

Much of the spread of freshwater pests within the Auckland Region has been through deliberate introductions or associated with other deliberate pest liberations. Once established the management options for the water body is very limited, especially submerged weeds and pest fish. Therefore prevention of establishment of these transformer pests (those which transform an ecosystem in a profound and often irreversible direction) is essentially the only way to protect the few freshwater resources of the region that are not yet severely impacted.

To develop strategies to manage these pest species Auckland Regional Council has contracted NIWA to assist with their development of a freshwater pest management plan for the region. This project involved:

  • Collection of baseline data on pest (plants and fish distribution) and identify their threats to Auckland water bodies, including lake, drain and ornamental pond surveys;
  • Prioritising lakes for regional importance;
  • Identifying weed introduction pathways and evaluating risks, including urban fish ponds as a potential weed sources;
  • Suggested surveillance and control options for these species.

Auckland Regional Council technical publication TP305 305

Last updated: 2019-03-18