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Monitoring shellfish safety

Paul McNabb of the Cawthron Institute in Nelson describes the system they use to monitor shellfish safety. He explains how toxins are detected in shellfish using liquid chromatography-mass spectrometry (LC-MS). Cawthron has become a world leader in developing such methods to detect toxins in shellfish. These methods are of international interest because they replace the need to use mice to detect toxins.

Jargon alert: Liquid chromatography-mass spectrometry (LC-MS) is a process using specialised equipment to detect toxins in substances. The process can accurately determine the molecular mass of different toxins, giving scientists the clue to work out what toxin it is.


So in New Zealand, we’re constantly monitoring shellfish for algal toxins. If there’s a bloom of a toxic species – sometimes called a harmful algal bloom – then the shellfish become dangerous to eat, and that’s when warning signs will go out.

There is a system with shellfish to monitor the levels of certain toxins within those shellfish, and that’s what we’re doing at the Cawthron Institute. We monitor samples regularly from commercial harvest areas, and that information is used in both commercial harvest but also for recreational harvest to put warnings on beaches about what the risks from shellfish might be.

We’re using something called an LC-MS – a liquid chromatograph-mass spectrometer – and we set those up to look for toxins that are commonly found in shellfish.

Cawthron has been involved with developing new test methods for these algal toxins, and when we started 10 years ago, all of these toxins were tested using live animals. So there were mouse bioassays performed regularly on shellfish, and now we’ve developed these methods which use LC-MS, and instead of using mice, we’re now testing through chemical means for the toxins.

We were the first country to develop these methods which didn’t use mice, and now almost 10 years later, the European Union has legislated to make these methods mandatory throughout the European Union, so there has been an international shift away from using mice and towards using technologies like LC-MS.

Cawthron Institute
Miriam Godfrey, NIWA, Chang et al. (2005)
Jarrod Walker
Maritime New Zealand


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