Perhaps the most telling thing about the investigation into an oyster parasite outbreak on Stewart Island is the question it didn’t try to answer. David Williams delves into the recently-released report.

In June last year, three weeks after it was announced that a deadly parasite had been found in farmed oysters on Stewart Island, angry residents demanded answers.

Stormy meetings were held in Bluff and at the island’s community hall. Fishermen and women wanted to know how bonamia ostreae had beaten the quarantine put in place by the Ministry for Primary Industries, after it was discovered in Nelson and Marlborough in 2015.

“There needs to be a big investigation because somebody bloody-well knows how it’s got there,” Barnes Oysters worker Max Russell said at the Bluff rugby clubrooms, according to a Southland Times report.

MPI readiness and response manager Geoff Gwyn assured the seething crowd that an investigation had begun. The results of the investigation are now known, but it’s hard to see how it’ll calm the still-raw feelings on Stewart Island – or ease the island’s economic pain after the destruction of oyster farming in Big Glory Bay.

At first blush, the MPI investigation into the outbreak of the oyster parasite appears to be a sign the issue has been taken seriously. The inquiry was quickly upgraded to a formal investigation, given the tenor of the “allegations and rumours” from the Stewart Island industry. Interviews were conducted over seven specific allegations.

The report, released last week to shock and surprise, leaves more questions than answers. Those questions include whether the probe was flawed from the start, considering the investigation specifically excluded trying to find the source of the Stewart Island outbreak – the very thing that was asked of the ministry at those stormy meetings last June.

Bonamia ostreae investigation report by David Williams on Scribd

The Christchurch-based MPI senior investigator who penned the report writes the investigation’s aim “was not to specifically identify how B.ostreae arrived in Stewart Island but whether any illegal activity could be associated with its arrival”. The report’s ultimate conclusion, after months of work, was: “There is no evidence to prove that any offences have been committed.”

In an emailed statement, MPI compliance investigation manager Gary Orr told Newsroom it’s still unknown how the disease spread to Southland. And last week, an MPI spokesman told Stuff there are now no active compliance investigations regarding bonamia ostreae in Big Glory Bay or Marlborough.

It’s likely, then, the source of the outbreak won’t be found, leaving taxpayers to pay compensation claims. It also leaves a question that should worry the public – without knowing how the parasite got to Big Glory Bay, how can the ministry hope to learn where the system failed and ensure it doesn’t happen again?

MPI’s handling of bonamia ostreae’s discovery in this country has been criticised since the start. Lab tests in January 2015 confirmed the oyster-killing parasite was present in Marlborough and Nelson. While the ministry advised the World Organisation for Animal Health, which is headquartered in Paris, it doesn’t appear to have issued a press release about it in New Zealand in 2015. It took until June of that year – five months later – for the ministry to implement controls on the movement of oysters, including spat, larvae or adult oysters. Marine farmers were then required to apply for permits to move stock.

The outbreak in Stewart Island has been described as the aquaculture industry’s equivalent of foot and mouth disease.

Clearly, the 2017 outbreak in Big Glory Bay showed MPI’s attempts to stop the spread didn’t work. But last June, MPI’s Gwyn dug his heels in. According to NZ Farmer, he told the Bluff meeting it was thought the permitting process and testing regime was sufficient to halt the parasite’s spread in 2015. He added: “I still have some confidence that wasn’t a bad call”.

It’s true, that with adequate tracing and controls bonamia ostreae could have been contained. The question is – just like the spread of the cattle disease mycoplasma bovis – how adequate was the MPI response?

What checks did it do in 2015 to trace oyster breeding stock movements? Did MPI knock on the doors of marine farms and demand to see their records? Did those companies, at MPI’s instruction, school their staff on the tell-tale signs of bonamia ostreae?

If not, why not? The removal of oyster farms at Big Glory Bay was a drastic measure to protect the Foveaux fishery. But it wouldn’t have been necessary if infected stock had been identified and removed earlier.

Let’s remind ourselves about the seriousness of this event. The outbreak in Stewart Island has been described as the aquaculture industry’s equivalent of foot and mouth disease. It’s surely dented the industry’s stated goal – supported by the previous Government – of growing annual sales to $1 billion in value by 2025.

Without well-kept records and a way to trace stock – like the much-maligned tracing system for cattle – how can the country ever hope to stop a biosecurity hazard?

Loose approach

After reading the MPI report into the Stewart Island outbreak, it could be argued some in the marine farming industry have a loose regard for the rules and MPI isn’t watching them closely enough.

One worrying passage of the report covers an oyster mortality event – the large-scale die-off of oysters – at a farm in Big Glory Bay. Interviews about the event, known as allegation ‘G’, showed “higher mortality rates”, of “up to 30 percent”, on oyster lines in Big Glory Bay. This was possibly at the end of 2016, almost two years after the industry was alerted to bonamia ostreae’s presence in the upper South Island. The MPI report said mortality records of oysters at the farm “were not recorded as it was impractical to do so”.

That’s unacceptable for many reasons. High die-off of oysters is a possible sign of bonamia ostreae. And marine fishers are expected to keep records about stock numbers, particularly to avoid the spread of what the Biosecurity Act calls “unwanted organisms”.

Another claim of wrongdoing in the MPI report, known as allegation ‘F’, was that an oyster farmer brought larvae back to Invercargill, by plane, from the January 2015 Auckland Seafood Festival. That was just two weeks before bonamia ostreae was found at an oyster farm in Port Underwood, in Marlborough, where the larvae came from.

Two people interviewed said the “12-to-18” larvae were destroyed “by simply tipping them onto the floor” – a claim about which the MPI investigator said “there appears to be no obvious motive to fabricate this”.

The report said this was “likely a breach” of the rules. Under their licences, oyster farmers can only obtain stock through what’s called an “authorised licenced fish receiver”, or through specific approvals. However, because this supposed breach happened in January 2015, it was outside a two-year limitation in the Fisheries Act.

The MPI investigation failed to find “non-compliance” in Stewart Island and Bluff that could have led to prosecutions. But what if “compliant” behaviour led to bonamia ostreae’s introduction?

Last June, MPI’s Gwyn told those gathered at the Bluff rugby clubrooms it was entirely possible the disease could have arrived in Stewart Island before controls were put in place in June 2015. It’s troubling to think that now, 10 months later, MPI still doesn’t know the answer to that question.

The problem with that line of inquiry is, of course, it would throw the spotlight back on MPI and its initial response three years ago. In the absence of evidence of illegal behaviour in Big Glory Bay, it seems the hard questions should be directed at MPI.

On the evidence of the oyster and cattle infections, it’s hard to argue it’s capable of containing a major biosecurity threat.

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David Williams is Newsroom's environment editor, South Island correspondent and investigative writer.

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