On 1 July 2025, NIWA merged with GNS Science to become Earth Sciences New Zealand.

Stopping the gold clam: It's now or never

A NIWA-led programme to develop effective, and culturally-attuned strategies for managing the freshwater gold clam.

Stopping the spread of the freshwater gold clam (Corbicula fluminea) is of critical importance for preserving native biodiversity, protecting infrastructure, and maintaining the cultural and recreational value of Aotearoa-New Zealand's waters. 

Alongside establishing practical control methods, the research programme will determine the gold clam’s ecological, social, cultural and economic impacts in Aotearoa-New Zealand, and predict its spread for early detection and targeted intervention.

The gold clam invading the Waikato River
Watch Video
This MBIE-funded Endeavour research programme will: 
  • Understand the impacts of the gold clam (ecological, economic, and cultural) 
  • Predict dispersal and future establishment enabling the prioritisation of locations for monitoring and early intervention 
  • Develop a suite of effective interventions (tools) to reduce the risk of transfer and to manage the gold clam at different scales.

Key collaborators include NIWA, Ngaati Koroki Kahukura, Waikato Tainui, Raukawa, University of Waikato, and international experts. 
gold_clam_strategies_figure.

From the field

Juvenile clam held by byssal thread during a Waikato River survey.
Michele Melchior / ESNZ
Juvenile clam held by byssal thread during a Waikato River survey.
Deployment of hydrophones with Dr Jenni Stanley (University of Waikato) and Gordon Tieman (Waikato Regional Council).
Michele Melchior / ESNZ
Deployment of hydrophones with Dr Jenni Stanley (University of Waikato) and Gordon Tieman (Waikato Regional Council). 
Earth Sciences NZ freshwater ecologist processing clam plankton tow collected from the Waikato awa.
Sniffing out trouble
Alex Fear / ESNZ
Sniffing out trouble. Scent detector dog Cino and University of Waikato Research Assistant Lucy Tannahill after the successful detection of a ‘test’ clam sample at the Earth Sciences NZ Hamilton facility. The Stopping the gold clam programme is providing guidance, clams and facility support for the detector dogs.
Detector dog scent
Michele Melchior / ESNZ
Detector dogs trained at the University of Waikato can detect extremely small samples. After clams spend two days in water, a cotton swab is dipped into the water; the tip of the swab is then cut off and placed in the gold sampler above. This sample is subsequently hidden on a boat trailer where the dogs cannot see it. 
Field visit with Ngaa Muka to identify suitable sites for developing and testing detection methods.
Michele Melchior / ESNZ
Field visit with Ngaa Muka to identify suitable sites for developing and testing detection methods. 
Earth Sciences NZ, Taranaki Regional Council and Blake Interns surveying clams
Deborah Hofstra, ESNZ
Earth Sciences NZ, Taranaki Regional Council and Blake Interns surveying clams by sieving lake substrates (sampled by the team in waders) from Lake Rotomanu following a drawdown, to get a better understanding of the clams abundance. This information that is needed to support the development of the next stage of the response.
Team at Bob's Landing
Alex Fear, ESNZ
They’re not lying down on the job; they’re scanning the lakebed for an invader. Earth Sciences NZ ecologists and visiting clam expert from Ireland, Prof. Frances Lucy, at Bob’s Landing on Lake Karāpiro prior to a December 2025 lakeside hui.
One News filmed an invasive gold clam story after seeing the media release and video. This will run over the Christmas break.
Alex Fear, ESNZ
One News filmed an invasive gold clam story after seeing the media release and video. This will run over the Christmas break. 
Researcher Michele Melcheir shows kahui clams
Alex Fear, ESNZ
Researcher Michele Melcheir shows kahui clams and discusses ESNZ research at lakeside hui at Bob’s Landing, Lake Karāpiro. Aso presenting was visiting Irish professor Frances Lucy.
Presentation to Karāpiro Lake users group meeting in October of Earth Sciences NZ decontamination research and process.
Michele Melchior, ESNZ
Presentation to Karāpiro Lake users group meeting in October of Earth Sciences NZ decontamination research and process.
MPI Ambassador training at Karāpiro lake 16 November 2025 presentation by Earth Sciences NZ researcher Brian Smith.
Brian Smith, ESNZ
MPI Ambassador training at Karāpiro lake 16 November 2025 presentation by Earth Sciences NZ researcher Brian Smith.
dive team
Michele Melchior, NIWA
A dive survey of Lakes Maraetai and Karaapiro was conducted in May 2025. Multiple sites were surveyed as part of the programme aim to assess changes in population structure and spatial spread over time. This survey will be repeated in 2026 and 2027 to understand how the abundance of clams and kaakahi at these different sites changes.
Corbicula_fieldwork_Melchior (4).jpg
Michele Melchior, NIWA
NIWA team and Ngati Koroki Kahukura processing clams (measuring and counting) following clam dive surveys at Lake Karāpiro, May 2024.
Filter traps are being used to study the invasive gold clam (Corbicula fluminea) in the Waikato River.
Stuart Mackay
Juvenile gold clams are difficult to detect in aquatic environments due to their small size. To survey gold clam infested environments NIWA are testing Hester-Dendy multi-plate samplers. In March 2025, 16 samplers were deployed at Bob’s Landing, Lake Karāpiro.
Using a bathyscope or underwater viewer to detect clams
Maddy Brennan, NIWA
Using a bathyscope or underwater viewer to detect clams.
2025_02_GOLD CLAM HUI_LO-RES_brennan-3450
Maddy Brennan, NIWA
Lakeside clam hui at Bob’s Landing Karāpiro February 2025.
clam
Maddy Brennan, NIWA
Lakeside clam hui at Bob’s Landing Karāpiro February 2025.  NIWA and visiting scientist Dr Cao gather with iwi to discuss the invasive gold clam.
nternational collaboration - Brian Smith (NIWA) and Dr Yu Cao (Wuhan Botanic Gardens, Chinese Academy of Science) examining the clams at the lakeside clam hui
Maddy Brennan, NIWA
International collaboration - Brian Smith (NIWA) and Dr Yu Cao (Wuhan Botanic Gardens, Chinese Academy of Science) examining the clams at the lakeside clam hui.
Collecting clam samples for lab work at Bob’s Landing February 2025
Maddy Brennan, NIWA
Collecting clam samples for lab work at Bob’s Landing, February 2025. 
Using NIWA’s bespoke clam net enables us to collect clams quickly and efficiently. At Bobs Landing, we collected 4,000 in 30 minutes.
Maddy Brennan, NIWA
Using NIWA’s bespoke clam net enables us to collect clams quickly and efficiently. At Bob's Landing, we collected 4,000 in 30 minutes.
Corbicula_fieldwork_Melchior (3).jpg
Michele Melchior, NIWA
Vijuan Kahara Paki (NIWA) sieving substrates for clam detection at Lake Maraetai, May 2024.
gold clam survey sorting
Michele Melchior, NIWA
Research team sorting and collating samples from the May dive survey in Lakes Maraetai and Karaapiro.

    In the lab

    A single D shaped clam larvae in natural sample with detritus and phytoplankton viewed under 100x magnification. What we observe when looking for them in water column samples.
    Karen Thompson / ESNZ
    A single D shaped clam larvae in natural sample with detritus and phytoplankton viewed under 100x magnification. What we observe when looking for them in water column samples. 
    Gold clams following exposure to a benthic barrier (EPDM matting) during experimental suppression trials.
    Michele Melchior / ESNZ
    Gold clams following exposure to a benthic barrier (EPDM matting) during experimental suppression trials. 
    Gold clam larvae under microscope
    Brian Smith, ESNZ
    Gold clam larvae under the microscope. These juveniles are around 0.2 to 0.3 of a mm making them almost impossible to see with the naked eye. For prospective the average size of a pinhead is 1.5 mm. These are recovered from the passive samplers at Bob’s Landing in March/April 2025.
    Native plant, Potamogeton ochreatus, under assessment at NIWA's Ruakura Aquatic Research Facility.
    Maddy Brennan, NIWA
    Research is been undertaken at NIWA’s Ruakura Aquatic Research Facility and by our international collaborator Dr Yu Cao (Wuhan Botanic Gardens) to understand the impact of high clam population densities on aquatic plants.
    gold clam lab work
    Maddy Brennan, NIWA
    NIWA Freshwater ecologist Dr Michele Melchior in the Hamilton lab dissecting clams to assess their reproductive ecology.
    Dissecting adult clams to assess reproductive rates.
    Maddy Brennan, NIWA
    Dissecting adult clams to assess reproductive rates.
    Dissections help us understand the anatomy and function of this newly introduced invasive species and how they are adapting to the New Zealand environment.
    Maddy Brennan, NIWA
    Dissections help us understand the anatomy and function of this newly-introduced invasive species and how they are adapting to the New Zealand environment. 
    clams
    Maddy Brennan, NIWA
    NIWA has received permits and permissions to collect, hold and culture this invasive species in our laboratories (PC2).

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      In the media

      • Link to source page

        "Now or never": fight against invasive clam gets critical boost

        Media release
        19 September 2024
        NIWA has been awarded $10.2m to investigate an invasive clam that was only recently discovered in New Zealand waters.
        Invasive species

      • Link to source page

        Gold clams

        It’s breeding season for invasive clam

        Media release
        20 November 2025
        Earth Science NZ researchers are seeing signs that the breeding season for the invasive freshwater gold clam (Corbicula fluminea) has begun.
        Freshwater
        Invasive species
        Lakes