Threat to oyster beds

Press, 11 September 1986, Page 20

Threat to oyster beds

Noisy noises, as most people know, annoy oysters; bonamia has far more serious consequences — it kills them,

indiscriminately and rapidly. The appearance of bonamia, a parasite, in the oyster beds of Foveaux Strait threatens the existence of the beds and, with them, a $lO million-a-year industry and the livelihoods of all associated with it.

The strictly controlled season for Bluff oysters, regulated to prevent exploitation of the Foveaux beds beyond their capability to replenish themselves, was five weeks shorter this year when dredgers in the western half of the strait were landing great numbers of dead shellfish. The Ministry of Agriculture and Fisheries has dispatched the research vessel Kaharoa and its experts in fish parasitology to the beds. More than 1200 samples will be taken and, on the basis of the findings, a decision will be made as to whether there will be an oyster season next year.

Oysters might pride themselves on being fish that are pretty hard nuts to crack; but they are easy prey to bonamia. Since the beginning of this year’s shortened season the parasite has spread from the extreme

western beds to the middle of the strait. That is rather like foot-and-mouth disease being discovered in Southland in May and wiping out livestock as far north as the Wairarapa by August — except that foot-and-mouth can be more easily quarantined and contained.

In Europe, where the parasite was first discovered in French oyster farms in 1979, bonamia has spread rapidly to become endemic to all European oyster fisheries except those of Ireland. The export industry for oysters there has been ruined. The big question for the scientists is why the parasite has suddenly taken over in Foveaux Strait. How, indeed, did it arrive? If this is a naturally-occurring and cyclical phenomenon, the beds might well recover. If not, who knows?

The 300 or so people in the industry whose jobs hang in the balance are not alone in their apprehension; thousands of New Zealanders have their own special interest in the treat. It would be a tragedy for them all if bonamia puts the lie to the declaration of Christopher North’s Ettrick Shepherd: “there’s really no end in nature to the eating of oysters.”