Freshwater biosecurity

Freshwater pests (existing and potential) pose an intolerable threat to New Zealand's environment and economy, and are of concern to both the public and those responsible for their management. As the pressure from introduction and spread of freshwater invasive species escalate, there is also an increasing strategic need for preventative strategies based on enhanced border control, public education, formalised surveillance strategies and investment in pest control. The goal of this programme is to support the New Zealand Biosecurity Strategy by reducing the risk of new freshwater invasive species entering and establishing, and by preventing or minimising impacts of resident alien invasive species on freshwater values.

Programme Leader: Dr Deborah Hofstra


  • Risk assessment knowledge and tools. Identifying potential and emerging threats to New Zealand's freshwater ecosystems from the impacts of invasive non-indigenous species. Discovering the mechanisms by which they are transported, become established and adversely impact core environmental, economic, social and cultural values.
  • Ecosystem impacts, values and surveillance. Evaluating biosecurity risks and ecosystem impacts. Developing better protection priorities and surveillance capability, including early detection of high risk aquatic species. Developing robust sampling designs to establish the current state of rivers and lakes (baseline inventory), and monitoring ecosystem impacts and rate of change.
  • Biosecurity barriers to restoration. Invasive species and habitat degradation poses a range of different barriers to restoration initiatives. We will investigate the links between our biosecurity and freshwater restoration work.
  • Management and mitigation of aquatic pests. Developing best practice tools and technologies for preventing the establishment of, or eradicating, newly-arrived species, and mitigating impacts of established pests.

Current research projects

  • Predicting the risk that pest species pose to our freshwaters
  • Assessing pathway risk for pest introduction
  • Remote sensing of aquatic vegetation
  • Environmental target setting with LakeSPI
  • Decontamination protocols for freshwater pests
  • Selective weed control using biodegradable benthic barriers
  • Developing smarter use of aquatic herbicides
  • Best practice guidelines for aquatic weed management
  • Developing tools to support in-lake restoration
  • Threatened plant ecology and restoration
  • Investigating the effects of didymo on trout fisheries
  • Nutrient management to control didymo blooms
  • Control of invasive pest fish using attractant baits

Historical research projects

Primary NIWA Team

Dr Deborah Hofstra, Ms Mary de Winton, Dr Cathy Kilroy, Dr Cindy Baker, Ms Tracey Burton.

Key science collaborators

  • Department of Conservation, NZ.
  • Prof Hulme, Lincoln University, NZ.
  • Landcare Research, NZ.
  • Dr Getsinger, US Army Corps of Engineers, Research and Development Center, Mississippi, USA.
  • Dr Madsen, USDA ARS, Davis California, USA.
  • Dr Netherland, University of Florida, USA.
  • Dr Richardson, North Carolina State University, USA.
  • Dr Dugdale, Agriculture Victoria, Australia.
  • Dr Hussner, Institute für Biochemie der Pflanzen, Heinrich-Heine University Dusseldorf, Germany.
  • Dr Hilt, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
  • Dr Gross, Université de Lorraine, France.

Recent publications 

See a list of our recent publications


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Freshwater Ecologist
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Freshwater Ecologist
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Principal Scientist - Freshwater Fish
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Freshwater Ecologist
SCUBA diver surveying the aquatic plant community (credit: John Clayton)
Research subject: Biosecurity