MPI Update On Corbicula (Gold Clam) Long-term Management March 2025
Corbicula moves to long-term management
Biosecurity New Zealand thanks all our partners who have contributed to the response effort to contain Corbicula and for your continued mahi to protect our waterways. The involvement of iwi, regional councils, river and lake users, and other agencies has been critical throughout the response phase, and will continue to be key in helping stop the spread in the long-term.
The Freshwater Biosecurity Partnership Programme involves key partners Biosecurity New Zealand, Department of Conservation, Fish and Game New Zealand, Land Information New Zealand, Tūwharetoa Māori Trust Board, other mana whenua, power companies, Te Uru Kahika (regional council collective), and industry groups.
The partnership programme works to understand and manage regional and national pathways through which significant freshwater pests are spread. Its focus is to increase knowledge, share expertise, develop best practice for management, and support the Check Clean Dry campaign and other freshwater biosecurity operations around the country.
With Corbicula moving to long-term management, this will be the last newsletter from the Corbicula response. Biosecurity New Zealand and our partners will continue to update our websites as things develop, so keep an eye on those. Future updates on the management of the freshwater clam will be included in the Check Clean Dry newsletter.
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The contact email address for Corbicula is now corbiculalongterm@mpi.govt.nz
Corbicula Collaborative Long-term Management Plan
The focus of the Corbicula fluminea Collaborative Long-term Management Plan is to contain the clam to the current known areas in the Waikato catchment area, reduce its impact where feasible, and develop tools to achieve this.
A national surveillance strategy, and a rapid assessment plan for new incursions will be developed under the plan. Other work includes research to better understand the clam’s impact on our waterways and expanding public awareness of Corbicula.
The pest management directorate of Biosecurity New Zealand has overall responsibility for long-term management, with oversight by the partnership programme steering group. Local councils and the Department of Conservation will lead operational delivery of the plan in partnership with iwi.
See the plan on the MPI website
Rapid Assessment Plan
A Rapid Assessment Plan is being developed to provide guidance in the event of a new detection of Corbicula outside the Waikato River controlled area. If a new detection is confirmed, a Regional Corbicula Working Group involving mana whenua, councils, the Department of Conservation, research providers and Biosecurity New Zealand would be established to manage the incursion.
The group will make decisions on the feasibility for implementing any regulations, population delimiting or elimination actions, and oversee the planning of this work.
It is pleasing to see all this activity to help river and lake users understand what they need to do to contain the Corbicula clam to the Waikato River.
Surveillance update
Biosecurity New Zealand’s aquatic readiness team is finalising a national Corbicula surveillance plan, which will soon be shared with regional biosecurity partners. The plan aims to maximise the likelihood of early detection of Corbicula in areas of New Zealand where the species has not yet been detected.
Key recommendations in the plan include a substantial increase in the number of eDNA samples collected per sampling unit, and the use of visual sampling techniques, such as benthic dredge tows. Early detection allows for timely management and intervention processes, significantly increasing the chances of successful containment.
Biosecurity New Zealand is collaborating with regional partners for eDNA surveillance of 12 high-risk waterbodies across the country. This is being implemented locally by regional partners and applies a higher eDNA sampling rate than previous efforts. Visual sampling techniques are planned for later this year.
Lake Ōkataina automated gate
A new automated gate arm has been installed at the Lake Ōkataina boat ramp, allowing boaties who have followed the Check Clean Dry procedures to access the lake from the boat ramp.
The gate and its installation have been funded jointly by the Bay of Plenty Regional Council, Rotorua Lakes District Council and Biosecurity New Zealand.
New signs at The Wash Place, 338 Te Ngae Road, explain the process for lake users to access the Lake Ōkataina boat ramp.
Boaties must follow these steps:
· Wash your craft at The Wash Place according to the instructions at the site.
· Scan the QR code in the wash bay using a phone camera.
· Fill out and submit the online form while at The Wash Place to receive 2 PIN access codes (the area is geo-fenced).
· Use the first 4-digit PIN received by email and text to open the gate at the boat ramp. You must use this PIN within 2 hours of receiving it.
· Use the second PIN when exiting the lake.
Detailed instructions are available on the Rotorua Te Arawa Lakes Programme website Lake Ōkataina new automated boat ramp gate system Rotorua Lakes
See details of the Controlled Area Notice on the Biosecurity New Zealand website Rules to stop the spread of Corbicula.
If users have any problems with the PIN a sign at the gate has contact details for assistance. Note, there is no overnight parking or camping allowed at the Lake Ōkataina scenic reserve.
Taupō Aqua Park
Treatment to eliminate Corbicula australis from the lagoon near Taupō began earlier this month. There has been a positive response with many dead clams surfacing following application of the treatment. Treatment will take up to 10 weeks and includes monitoring the clam population to provide confidence that the clam has been eliminated from the lagoon.
Tūwharetoa Māori Trust Board: championing summer waterway protection
It’s been a big summer of mahi for local iwi who have joined with agencies to champion protecting Taupō lakes and rivers from invasive species, including successfully processing thousands of competitors for the Ironman 70.3 World Championship.
Tūwharetoa Māori Trust Board holds title to Taupō Waters, which includes the lakebed of Lake Taupō, the Waikato River up to Te Toka a Tia (the Rock of Tia), Huka Falls, and the beds of various rivers and streams flowing into Lake Taupō. This significant responsibility drives its efforts to preserve these waters.
Iwi teams joined the Department of Conservation (DOC), Waikato Regional Council and Biosecurity New Zealand to engage with those at boat ramps and on the water, to ensure they understand best practice for cleaning craft and equipment.
In December last year more than 6,000 athletes from around the world arrived in Taupō for the Ironman 70.3 World Championship. Trust kaimahi joined with DOC and Council staff to speak to each triathlete at registration to determine if they had followed the Check Clean Dry procedures. Only 15 had not done so, and their gear was washed for them.
Trust kaimahi also engaged with local fishers and boaters at fishing spots and reached out to whānau and hāpori (community) to share Check Clean Dry information, educate about the shared responsibility to protect our water ways, and remind them about water safety. The Trust also monitored commercial operators during the season.
Ka pai to the Trust and our partners for this mahi, which underscores the need for a collective effort as we continue the work to prevent the spread of Corbicula.
Ballast-tank treatment trials
Biosecurity New Zealand collaborated with Waikato Regional Council and the New Zealand Water Ski Racing Association to conduct trials of a hot-water treatment.
The one-off trial used a system developed by the council to treat the inside of ballast tanks with hot water (heated to 50-55 degrees) for 5 minutes, a treatment scientifically proven to kill juvenile Corbicula.
The "hot water trolley" system was successfully tested on 22 boats with hard ballast tanks. The trials showed that ballast tanks could be successfully cleaned at a high temperature and decontaminated prior to entering the waterways.
A pilot ballast-tank treatment service is planned to address the need for an accessible ballast-tank cleaning option for boaties who use Waikato waters. Work is underway to develop service specifications, a verification system, and to identify a suitable Waikato-based service provider
Keeping the momentum going at Karāpiro
The Lake Karāpiro ambassador team is now half-way through the busy season of events that take place near where the clam was first found in May 2023. Lake Karāpiro is a major hub for water sports activities, hosting local, regional and national events each year.
A flagship event, the week-long Waka Ama Nationals, attracted a record of nearly 4,000 paddlers and thousands of spectators in January. The ambassador team worked closely with the event organisers on pre-event communication and making sure everyone was aware of the Check Clean Dry requirement to prevent the spread of Corbicula.
Ambassadors were on-site every day, with interactive activities to draw young people to the marquee. Over the week, they engaged with a large number of paddlers and supporters as well as overseeing boat washing and ensuring best practices were followed.
Almost 4,000 rowers and 13,000 spectators have been exposed to the Check Clean Dry messaging at recent rowing regattas.
Over the busy Christmas period, the team trialled an electronic board at the entrance of Mighty River Domain and nearby Hora Hora Domain, to reach the free independent water users coming to Lake Karāpiro. This was successful in grabbing the attention of recreational users and campers.
With Biosecurity New Zealand support, an informative video was shared on the Lake Karāpiro Facebook page attracting nearly 1,000 views to date. It was also shared by stakeholders to their communities.
The final large event of the season, the Maadi Rowing Cup for high school students, will attract 2,300 participants and around 12,000 spectators to Lake Karāpiro in March.
A group of young paddlers is schooled up on the invasive clam during the Waka Ama Nationals at Lake Karāpiro in January.
Connecting with Waikato River users
A team of Waikato Regional Council (WRC) freshwater biosecurity advocacy students were busy throughout the summer period greeting river users on boat ramps in the CAN zone and educating them about preventing the spread of gold clams. Their messages were well-received, with most of these water users wanting to learn more and take action to stop the spread.
The results of surveys taken during this time proved the need for this advocacy among free, independent water users: of the 361 people surveyed at boat ramps within the Controlled Area Notice area, 42% were not aware that Corbicula had been found in the Waikato, and 62% had not heard about Check Clean Dry.
Many of these river users remembered the students on their second and third encounter and were able to repeat the key learnings to prevent spread.
The WRC ambassadors also attended the Taupō Ironman event in support of the Tūwharetoa Māori Trust Board team, and several events at Lake Maraetai.