After river closures due to rain and sewage spills, not to mention the market crashes that arrived with COVID-19, now the river has been closed due to a detected algal bloom.

"It has been a nightmare," oyster farmer Delphine Tessier said.

"Since January we have been closed 50 per cent of the time! Right now we are waiting for the results of the latest tests to see if the river reopens or not."

Routine testing by farmers after rainfall on June 10 returned a positive test for the presence of a biotoxin, closing the river and also the availability of commercial shellfish product from the Nambucca River harvest areas.

Ten days ago, on July 1, a biotoxin screening test returned positive results for Paralytic Shellfish Toxins (PST), which come from algae called dinoflagellates.

A spokesperson for the NSW Food Authority said this discovery delayed the reopening of the harvest areas while further, more complex testing was carried out to discover the level of toxin present.

"If this result is negative or less than the regulatory limit the harvest areas can reopen; provided all other conditions of their management plan for the area are met," the spokesperson said.

"The additional testing is part of the routine monitoring process to safeguard consumers."

Long time oyster farmer James Ford said there had been some previous algal blooms in the river but not for a long time.

"We are however seeing more of this occurring because water quality is dropping statewide," James said.

"It is the effect of humans, animals and farm chemicals - it takes its toll."

He said he was hopeful the river would reopen soon:

"Hopefully, if the oysters are fat and the demand is there, we can get on with some harvesting."

Maintenance and care of their oysters, means there is still plenty for farmers to do when sales are down.

"My son said all the setbacks this year just mean the oysters will be bigger and the prices better next year," Delphine laughed.

James was more sanguine: "You just look at the light ahead of you rather then the one coming right at you."

Results are expected in the coming days.

From the NSW Food Authority -

Algal blooms can occur anywhere along the coast and are normally the result of the surge of nutrient rich deep ocean water onto the continental shelf and can often be seen after rainfall events in estuaries and in river mouths.

Some of these algae produce harmful toxins that can build up in marine shellfish.

Paralytic Shellfish Poisoning (PSP) toxins can cause human illness. Symptoms can range from a slight tingling or numbness of the extremities to complete respiratory paralysis.

In fatal cases, respiratory paralysis occurs within 2 to 12 hours of consumption of the PSP contaminated food. Fortunately Paralytic Shellfish Poisoning is rare.

In NSW, commercially harvested shellfish must comply with a comprehensive food safety program. The industry closely monitors algal levels and rainfall, tests water and shellfish product and does not harvest when levels reach alert levels.

This program is controlled through the NSW Shellfish Program administered by the NSW Food Authority. This program assists commercial shellfish harvesters to control risks associated with harmful substances in shellfish.

Previous algal blooms in NSW shows we do not tend to experience high toxin concentration or prolonged algal bloom events. Most blooms seem to disperse within one-two weeks.

In the past 12 months, of 231 closures of shellfish harvest areas in NSW , there have been 23 closures due to algal blooms, of which five were due to a positive biotoxin result.

Closures are enacted because a bloom may result in contamination of a growing area.

Further information about recreational fishing and safe consumption can be found at www.foodauthority.nsw.gov.au/consumer/special-care-foods/recreational-harvest-of-seafood

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