Port's shellfish contaminated by toxic bloom

A bloom of toxic algae in Port Underwood has contaminated shellfish with a toxin harmful to humans.

The Nelson Marlborough Public Health Unit advised the public not to take or eat shellfish from inner Port Underwood west of a line drawn from Robertsons Point until further notice.

Routine testing of shellfish had shown "higher than acceptable levels" of the toxin causing Diarrhetic Shellfish Poisoning (DSP) in the area since March 5, according to the unit's medical officer of health, Dr Ed Kiddle.

Helen Smale, manager of the Marlborough Shellfish Quality Programme which conducts the tests, said although it had been years since the last DSP contamination the "vigorous systems" in place had ensured no contaminated shellfish from the area's mussel farms made it into supermarket tanks.

She said the algal bloom which created the toxin in the shellfish was a natural phenomenon and would rectify itself.

"The bloom will die and the toxin will depurate out of the shellfish, it doesn't harm the shellfish."

She said she was unsure how long the bloom will last. The latest test showed the algae were still increasing."We'll know what's happening when we get next week's samples."

Two consecutive tests with a negative reading for the toxin were required before it would be considered safe to take shellfish from the area.

Chief executive of the Marine Farming Association Graeme Coates said the contamination was a normal part of the industry and happened occasionally. "It's nothing exceptional or unexceptional here, it's just normal business."

He said he had not heard from any of the marine farmers in the area who had any problems stemming from the algal bloom.

Symptoms of DSP were diarrhoea, nausea, vomiting and abdominal pain, would be short in duration and occur within 12 hours of eating.

People should not eat kina, mussels, pipi, tuatua, oysters or cockles from the affected area, and cooking did not make the shellfish safe to eat, he said.

Fish, crab, crayfish and paua were unaffected, as long as the gut was removed prior to cooking, he said.

Apex Marine Farm owner Bruce Hearn, who grows 17.5 hectares of mussels in Port Underwood, said the bloom was "inconvenient and costly".

Mussels in the area were ready to harvest and there was about a three-month window left before they got too big and heavy, said Mr Hearn.

An extended closure was a grower's worst nightmare.

"I haven't lost any sleep over this at all, but if it's still here in a month's time I'll be getting agitated."

For more information regarding DSP contact the Marlborough Public Health Unit on 5201800 or 5209999.

- The Marlborough Express