Editorial: Did authorities fail oyster farmers?

Could the much-loved Bluff Oyster fall victim to a lethal of parasite?

Could the much-loved Bluff Oyster fall victim to a lethal of parasite?

EDITORIAL: The Ministry for Primary Industries (MPI) is working with oyster farmers and others to combat the parasite Bonamia ostreae, which was found in Big Glory Bay on Stewart Island two weeks ago.

Questions need to be asked about whether officials have moved swiftly enough to contain this outbreak, and indeed whether enough was done to stop the spread of the oyster parasite after it turned up in Marlborough waters in 2015.

Bonamia ostreae is not harmful to humans, but it is lethal to some species of flat oysters. Overseas, it is present along the European coast from Denmark to Spain, in parts of the British Isles and on both coasts of the United States.

A particular concern following its confirmation at two Stewart Island farms on May 24 is that it will now contaminate the Bluff oysters of Foveaux Strait.  

As with many types of biosecurity incursions, the problem is difficult to diagnose and extremely hard to manage. The parasite can spread not only from oyster to oyster, but along ocean currents and on vessels and machinery.

Farmers and fishers may only be aware they have a problem when large numbers of oysters die, and even then, they may not know they are dealing with this particular species of parasite.

An organism which closely resembles it, Bonamia exitiosa, has been endemic in the south for at least 30 years and at one time reduced the Foveaux Strait fishery to just 10 per cent of its pre-disease level. The industry was disrupted from 1985 to 1993, and again from 2000 to 2005.

It was probably inevitable that Bonamia ostreae would become established at different sites in New Zealand sooner or later, given the ease with which it seems to have spread in other parts of the world. Nevertheless, one Bluff oyster industry leader, Graeme Wright, has labelled MPI "incompetent" for its handling of the threat after it first appeared in Marlborough two years ago.

Wright said the MPI had scientific advice that the best course of action at that time was to remove flat oysters from the Marlborough farms, but that did not happen.

MPI said it introduced movement restrictions and increased monitoring.

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On Friday, the ministry said it was now working urgently to remove all flat oysters from marine farms in Big Glory Bay, and would work also with Marlborough farmers to remove flat oyster stocks there also, "to relieve disease pressure in New Zealand".

It acknowledged "strong feelings" in favour of quick action, but it said a rushed removal process might cause more harm than good by releasing more of the parasites. Compensation for farmers under the Biosecurity Act is being discussed.

The MPI has to deal with biosecurity threats on many fronts, from oyster parasites to fruit flies, to the ever-present threat of foot and mouth disease. Like any government department, it has to budget and marshall its resources to meet these competing demands the best way it can.

But it is worth asking why a more aggressive approach was not taken after Bonamia ostreae was found in Marlborough two years ago. If the iconic Bluff oysters end up victim to this strain of parasite, people will want to know why more could not have been done to stop its spread.


 - The Press


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