Ngā Riha Wai Māori freshwater pests workstream

Stopping the spread of invasive species

Ngā Riha Wai Māori began in 2019 to help contain and control invasive freshwater species.

The workstream is linked directly to the objectives of Te Mana O Te Taiao the Aotearoa New Zealand Biodiversity Strategy 2020, especially to reduce the biological threats and pressures to native species through management.

The workstream focusses on freshwater pest species primarily to:
Reduce the impacts of Noxious Fish (Schedule 3, Freshwater Fisheries Regulations 1983):

• koi carp (Cyprinus rubrofuscus)
• rudd (Scardinius erythrophthalmus)

Preserve so far as is practicable all indigenous freshwater fisheries, and protect recreational freshwater fisheries and freshwater fish habitat (section 6(ab), Conservation Act 1987):

• cuscuta (Cuscuta campestris)
• hornwort (Ceratophyllum demersum)
• gambusia (Gambusia affinis)
• gold clam (Corbicula fluminea)
• red-eared slider turtles (Trachemys scripta elegans)
• Other pest species that are considered a regional priority, such as lagarosiphon (Lagarosiphon major).

Programme objectives

Nga Riha wai-Māori | Freshwater Pest Species has developed a national strategy (PDF, 337K) alongside key stakeholders with the following objectives:

1. Effective and efficient operational delivery
2. Advanced capability and capacity
3. Cohesive interagency collaboration
4. Strong relationships with tāngata whenua and communities
5. Development of research and tools

Team and approach

The Ngā Riha Wai Māori | Freshwater Pests Species team includes three Technical Advisors, who primarily focus on the development of research and tools, and 13 regional rangers, who primarily focus on the management of priority pest species. The rangers have roles shared between this workstream and Ngā Ika e Heke (migratory fish), and work closely with Arawai Kākāriki (wetland restoration) and Ngā Awa (river restoration) rangers.

This workstream is closely aligned with the National Freshwater Biosecurity Partnership Programme, which runs the Check Clean Dry campaign. Led by MPI, it brings together DOC, Biosecurity New Zealand, Fish & Game, local government agencies, industry organisations and specific Māori entities to prevent the further spread of freshwater pests.

Research project summaries

• eDNA sampling in still freshwaters – field guide 
• Efficacy of single-species eDNA assays for invasive fish monitoring (PDF, 322K)
• Invasive macrophyte remote detection research (2022) (PDF, 3,074K)
• Invasive macrophyte remote detection research (2023) (PDF, 4,759K)
• Invasive macrophyte remote detection research (2024) (PDF, 874K)

Research project reports

• Assessment of barriers to koi carp migration, Ōhaupo catchment (PDF, 1,481K)
• Cuscuta campestris: parasitism of Bolboschoenus fluvitalis (PDF, 793K)
• Cuscuta campestris: host themes and preferences (PDF, 2,756K)
• Cuscuta campestris: Monitoring plan (PDF, 1,050K)
• Inventory of freshwater fish farms and associated biosecurity measures applied by regional and unitary councils (PDF, 944K)
• Mapping the incorporation of Te Ao Māori in the Freshwater Biosecurity system (PDF, 5,273K)
• Potential ecosystem impacts of biosecurity risks associated with freshwater fish farms (PDF, 1,197K)

Contact

For more information email info@doc.govt.nz.