The study — funded by Nelson science organisation the Cawthron Institute and the NZ Food Safety Science and Research Centre and conducted with the Institute of Environmental Science and Research and Dunedin company Southern Clams Ltd — is aimed at generating knowledge to help the shellfish industry in managing microbial risks.
Those risks come from viruses and bacteria, most of which come from wastewater from septic tanks or sewer overflows and waste discharges from boats.
While in New Zealand risk was well managed, it was vital to protect the local seafood industry for export purposes, Cawthron Institute research leader Carlos Campos said.
At present, if there was a contamination there had to be a blanket 28-day closure of the site, which was "quite penalising" for the industry.
It was hoped the study could come up with new criteria to reopen the growing sites in a more effective way, taking into consideration the public health risk and the industry’s needs.
"We are trying to come up with a protocol that shellfish farmers can use to monitor shellfish quality in the growing area.
"If we can do that, there is gains for the industry, gains for the consumer and gains for the regulators," Dr Campos said.
The study has been run in conjunction with Southern Clams Ltd, which harvests clams in the harbour for both the New Zealand market and niche markets in Europe, Asia and North America.
The company has been supplying the researchers with clam samples to study, a vessel for the researchers and local knowledge.
The study started about 12 months ago and has gone through several stages, including to simulate wastewater spill in the harbour using dye to trace and track a fake spill.
Samples of little neck clams have been collected from nine sites in the harbour so far and sent them to laboratories to be tested for bacteria, such as E. coli and human norovirus.
The researchers chose Otago Harbour because of its quality for growing shellfish and its location, Dr Campos said.
It was very important to protect the New Zealand shellfish industry as it grew and expanded into other export markets.
There had been "significant numbers" of contaminations in the US and Europe and it was important it did not happen here so New Zealand could continue exporting good-quality shellfish overseas.
