Anti-fouling paint used on the hulls of many New Zealand boats is leaching into the water and killing organisms in harbours and marinas.
The National Institute of Water and Atmospheric Research (NIWA) has just completed a major study into the leaching of copper from paints designed to stop unwanted marine life attaching to hulls.
It has discovered copper levels in some harbours and marinas are 20 times what is considered normal.
NIWA principal scientist Chris Hickey says shellfish species people eat have high levels of copper and they are killing marine life unnecessarily in some harbours.
Dr Hickey says Nelson Harbour and Milford Sound were the worst affected areas, along with several Auckland marinas and it is time to find an alternative to copper for boat hulls.