Tuesday, November 7, 2017
Sven Carlsson
SHELLFISH biotoxins are putting a halt to this week’s planned mussel harvest.
Opotiki district councillor and Whakatohea Mussels shareholder and retailer Barry Howe said a closure by the Ministry for Primary Industries had put paid to this week’s harvest.
“They have closed an area from Waihi to Opape,” he said.
“It’s a precaution more than anything else.”
The closure came into effect last Friday and Whakatohea Mussels was unable to harvest while the closure remained in place.
“Once we have received the all clear from the ministry, we’ll be back into it,” Mr Howe said.
He said algal bloom was a natural occurrence that was caused by an organism that has been around for thousands of years.
“They spawn and get toxic when they are breeding,” he said.
“It doesn’t damage the mussels and it can disappear in a few days.”
While the bloom was taking place, it affected “all shellfish around”.
Ministry for Primary Industries specialist adviser Piers Harrison said the mussels could potentially be harvested, but they had to be tested for paralytic shellfish toxins prior to releasing them to market.
“The mussel farm at Opotiki undertakes separate testing from MPI’s recreational shellfish biotoxin monitoring programme, to ensure any mussels sold are safe from harmful levels of marine biotoxins,” he said.
It was, however, much safer for the mussel farm to stall harvesting until the bloom had subsided, lest they end up with harvested mussels that could not be sold.
“Once the algal bloom has subsided the levels of toxins in the shellfish drop,” Mr Harrison said.
“For some shellfish such as tuatua or pipi it can take months for the toxin levels to drop to safe levels, whereas for oysters or mussels it is usually a lot quicker, days or weeks.”
Shellfish PSP warning
THE Ministry for Primary Industries (MPI) issued the public health warning on Friday, advising people not to collect or consume shellfish harvested in the area from Rogers Road (Pukehina Beach) to Opape.
Routine tests on shellfish samples taken from sites in the region have shown levels of PSP toxins above the safe limit of 0.8 mg/kg set by MPI. Anyone eating shellfish from this area is potentially at risk of illness.
Mussels, oysters, tuatua, pipi, toheroa, cockles, scallops, catseyes, kina (sea urchin) and all other bivalve shellfish should not be eaten an MPI release stated. The ministry stressed that cooking the shellfish does not remove the toxin.
Cooking shellfish does not remove the toxin.
Paua, crab and crayfish may still be eaten if the gut has been completely removed prior to cooking, as toxins accumulate in the gut. If the gut is not removed its contents could contaminate the meat during the cooking process.
Symptoms typically appear between 10 minutes and three hours after ingestion and may include:
numbness and a tingling (prickly) feeling around the mouth, face, and extremities (hands and feet); difficulty swallowing or breathing; dizziness; headache; nausea; vomiting; diarrhoea; paralysis and respiratory failure and, in severe cases, death.
People who become ill after eating shellfish from the area can phone Healthline for advice on 0800 61 11 16, or seek medical attention immediately. You are also advised to contact your nearest public health unit and keep any leftover shellfish in case it can be tested.
Monitoring of toxin levels will continue and any changes will be communicated accordingly. Commercially harvested shellfish – sold in shops and supermarkets, or exported – is subject to strict water and flesh monitoring programmes by MPI to ensure they are safe to eat.
Blooms frequent in Bay
THE Bay of Plenty gets frequent algal blooms. The Bay is a sunny place and has some of the warmest water in New Zealand, which circulate down from the Pacific Ocean.
Blooms often form and disperse in the currents of this region due to these growing conditions.
Some algae form resting cysts when conditions worsen and lie dormant on the sea floor until conditions improve.
A weather or ocean event may stir the cysts back into life and form another bloom.
Besides the Bay favourable growing conditions, some shellfish like tuatua and pipi can hold onto the toxin for a long time, even when a bloom has disappeared.
Ensure you obey biotoxin signs if they’re in place.