Day Sea Kayak Tour to Tiritiri Matangi Island

Kia ora
We need your help to stop the spread of Corbicula
The invasive freshwater clam is threatening our fresh waterbodies.
As an organisation that spends time in Auckland’s fresh water recreation areas, we need your help to prevent spread of the this pest.

Where it is currently found
Also known as the gold clam or Corbicula, the invasive freshwater clam was found in the Waikato River in May 2023 and is now firmly established from Whakamaru Dam (near Mangakino) to Port Waikato. In November 2025 it was confirmed in Lake Rotomanu in Taranaki Region, showing how easily it transfers between waterways and regions.

Fast to spread and virtually invisible
While adult clams are 2-3 cm, juvenile larvae are virtually invisible and disperse widely on currents. Juvenile clams can attach to, and survive on, any wet gear from an infected body of water. These clams reproduce rapidly and can clog water pipes, impact water quality and will crowd-out native species.

How you can help stop the spread
Please inform your members that the main way to stop them spreading into the Auckland region is to follow the Check, Clean, and Dry procedure for any equipment and gear used in bodies of freshwater, especially the Waikato River.
This includes:
· boats and trailers
· fishing gear or other recreational equipment
· wetsuits, clothing, footwear or any other gear that gets wet.
If you think you have seen the invasive freshwater clam outside of the known areas, please contact Biosecurity New Zealand on 0800 809 966 or complete an online reporting form at report.mpi.govt.nz
For further information on the invasive freshwater clam please check out the Biosecurity New Zealand website. Or contact Auckland Council at pestfree@aucklandcouncil.govt.nz

Check, Clean, Dry

To protect our freshwater waterways, follow these steps when you move between lakes, rivers, or streams:
Check – for what is visible
• Remove any visible material such as plant matter, mud or visible clams from your gear and leave it on the river or lake’s bank or put it in the rubbish.
• Drain all water from your boat, motor and gear (any wet item can spread the clam).

Clean – for what is not visible
• Blast your gear and craft with tap water onto grass, (so as not to spread the clam into stormwater systems or drains).
• For absorbent materials, use the most appropriate of the treatments listed below: Soak in hot tap water (50°C to 55°C) for at least 5 minutes, OR
• Soak in 5% bleach solution (5-litre mix = 250ml bleach in 4.75 litres water) for an hour, OR
• Freeze till solid (overnight), OR
• Soak in salt solution at 100ppt (parts per thousand) (5-litre mix = 500g salt in 5 litres warm water) for 4 hours.

Dry – to be sure
• Allow gear, clothing items and equipment (including watercraft) to dry completely, then keep dry for at least 48 hours (2 days) before using again.
• Ensure all areas where water has pooled inside the craft are also dried.