Toxic shellfish in Tauranga

Toxic shellfish in Tauranga

In the last couple of days there has been news of a number of people admitted to hospital in Tauranga with shellfish poisoning. There have been warnings out for some time now, advising people to avoid shellfish from the area after tests showed PSP (paralytic shellfish poisoning) toxins were present.  It might be coming from a  microalgae called Alexandrium catanella.


This story took me back to the late 90s, when scientists at Cawthron first raised the alarm about PSP in this region. Following the wakeup call in the summer of ‘92/93 when New Zealand shellfish industry experienced its first major closures caused by algae blooms, a very extensive surveillance system was set up. One sampling station was at a marker buoy about 5 km out from the entrance to Tauranga Harbour. One day, some microalgae identified as Alexandrium catanella were found in the water sample from that spot. That was a big surprise as the organism had never been found in New Zealand before and, what’s more, had a very bad reputation overseas.

Alexandrium catanella produces various quite potent toxins, including saxitoxins. Saxitoxin is one of only two biotoxins listed in schedule I of the Chemical Weapons Convention (ricin is the other), with very tight controls on possession and shipment.

When she learned of this discovery, the technical expert representing the shellfish industry felt it might be a good opportunity to give the industry a “rev up”. Things had been relatively quiet for a while and even though the industry was developing a very good biotoxin management program she was determined to stop any complacency creeping in. We should issue a press release, she thought, pointing out that it was the first sighting and that several years back a bloom of Alexandrium catanella had resulted in a dozen or so deaths (in Chile, I think it was). So media release went out.

Rather to my surprise it was picked up by Radio New Zealand and the next morning I got a call from one of the producers of their morning show “Nine to Noon”. At that time it was hosted by Kim Hill. Would I be willing to be interviewed live by Kim at around 1100?

Kim Hill is an award-winning radio journalist, highly intelligent, very interested in science and has a great reputation for penetrating questions. I have seldom been as nervous, waiting for the call. I’d made the mistake of discussing it with some of the Cawthron staff so the knowledge that every radio in the building would be turned on did not help.

The interview started very well. The facts were fairly straightforward, but I had a real balancing act to perform. We wanted the public to take these warnings seriously but also reassure them that commercially farmed shellfish was safe to eat.

I must have spent too much time describing the deaths in Chile because then Kim started asking questions about commercial shellfish. I quickly switched to reassurance mode, describing in some detail how the new biotoxin management plan worked. “If everything is as safe as you suggest and people have nothing to worry about, why did you issue a media release?” she asked. At the time that question threw me. All I could think of was that I couldn’t say we wanted to shake the industry up a bit, to make sure they stayed on track. “Good question” I replied. “Yes, I know” she said. “Are you going to answer it?”

I thought rapidly: “well, being a first sighting it’s scientifically very interesting” was my feeble response. I could imagine the expression on her face as she snorted. “ Good grief! I have visions of scientists in white coats running around shouting ‘ whoopee! We’ve discovered the bubonic plague!’” I could only agree that it was a fairly silly response. I was not doing well. “ My God!” she exclaimed. “ Who in their right mind would ever eat shellfish?”

This was bad. I could imagine the managing director of one of the shellfish exporters reading the transcript of this interview. Suddenly I had an inspiration. “Well, I do. I eat mussels four times a week, for my arthritis”. “ Really? Do they work?” She asked. At that time they really did work. I had managed to get off all my medications, a situation which lasted for seven or eight years.

So the next 10 minutes was spent discussing my health problems and the virtues of Greenshell mussels. A lucky escape!


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