Shellfish warning continues

After two years, people are still being warned not to eat shellfish collected along the Western Bay coastline because they could be contaminated. Photo / Mark McKeown

A health warning against eating shellfish collected along the Western Bay coastline has now been in place for more than two years and officials say it will not be lifted until toxin levels drop.

Toi Te Ora Public Health Service medical officer of health Jim Miller said recent sample results showed it was still unsafe to eat shellfish taken from the region's beaches.

"We won't consider lifting the warning until we see the levels drop in at least two or three samples in a row as results can be variable and unpredictable."

The latest warning came before an outbreak of paralytic shellfish poisoning in 2012 when 27 local residents ate contaminated shellfish. A number were hospitalised.

The warning applies to all bi-valve shellfish including mussels, pipi, tuatua, cockles, oysters, scallops as well as cat's eyes, snails and kina.

It covers the coastline from Tairua to Whakatane Heads in the Eastern Bay of Plenty. The warning includes Tauranga Harbour, Maketu and Waihi estuaries, Matakana and Motiti islands, and all other islands along this coastline.

Previously, a long-term warning was in place from December 2009 to March 2011. Tilby Point has a permanent health warning.

Bay of Plenty Regional Council science manager Rob Donald says the warning for shellfish is due to elevated levels of PSP toxins.

"There is nothing the regional council can do about the presence of PSP, as the algae that cause the problem are naturally occurring in the ocean," he says.

Water is monitored regularly at about 80 river, stream, estuary and beach sites. The council tested for faecal coliforms, e.coli and enterococci, all indicators of faecal contamination.

Elevated levels meant there was a heightened risk of illness from viruses, giardia and pathogenic bacteria, he says.

But water quality had been good.

"This year, the water quality has been good with a few cases of elevated faecal coliform levels that quickly returned to low levels."

However, Tilby Point had a number of sources of faecal contamination including the occasional sewage overflow, septic tanks and inputs from the Wairoa River and the council was actively working with communities to address issues.

"Unfortunately there is no one 'silver bullet' option for Tilby Point as there are so many potential sources of faecal contamination."

Shellfish were filter feeders and could directly feed on bacteria and other microscopic organisms from faecal contamination, Mr Donald said.

"These can accumulate in the gut of the shellfish and can in turn be consumed by people."

Paralytic shellfish poisoning

*Toxin can cause numbness and tingling around the mouth, face, hands and feet; difficulty swallowing or breathing; dizziness; double vision; and in severe cases, paralysis and respiratory failure.
*These symptoms can start as soon as one-two hours after eating toxic shellfish and usually within 12 hours.
*Anyone suffering illness after eating shellfish should seek urgent medical attention.
*Up-to-date information on the toxic shellfish health warning can be found at 0800 221 555 or www.ttophs.govt.nz under health warnings.