Parasite hits scallop beds

Scallops affected by the parasite have been found in several locations around New Zealand.

Discovery of fatal organism could explain failure of shellfish near Great Barrier Island.

Concern is stirring over the health of several scallop fisheries after an investigation by scientists which has detected the spread of a new parasite to North Island waters.

The Ministry for Primary Industries is expected to issue a report today confirming the presence of Perkinsus Olseni around Great Barrier Island and Great Mercury Island off the Coromandel Peninsula, as well as in Marlborough's Pelorus Sound.

That follows the first detection of the parasite - which can prove fatal to shellfish but is not deemed a threat to human health - in New Zealand scallops in the Marlborough Sounds in December, although it has previously been found here in mussels and clams.

Auckland recreational diver Greg Hurt, who alerted the ministry after photographing "very sick"-looking scallops with no roe off Great Barrier and comparing them with healthy specimens he gathered from the Hauraki Gulf on the same day in January, understands an investigation by scientists has also found problems with their digestive systems.

Parasitic cysts are also believed to have been found in scallops surveyed around Great Mercury Island, part of a lucrative commercial fishery.

The ministry would not comment on its findings last night, but said it hoped to issue a statement today.

Mr Hurt believes the parasite may explain a mass die-off of scallop beds off Great Barrier, where he has dived for the delicacy - a favourite of his wife - for about 35 years but which is now off-limits to commercial harvesters. He told the Herald that of 19 beds from which he used to collect scallops, all except one had died off in the past five years.

That was where he collected the pale specimens in the photo sent to the ministry. "They're fading fast - you can't get a decent scallop at Barrier that I know of," he said.

Whangamata Seafoods co-owner Peter Sopp said earlier that the ministry had advised him some weeks ago of a potential new biosecurity threat, but he needed to learn more details before consulting skippers of his fishing fleet about whether any beds in their area needed isolating.

He said the seven-vessel fleet harvested 35 tonnes of scallops last season, down from about 50 tonnes for each of the previous three years, which followed tight voluntary controls to rebuild previously depleted beds.

Scallops
•A sought-after shellfish delicacy fished commercially and recreationally around New Zealand.
•New Zealand scallops are an export product but are mostly eaten domestically.
•The size and number of scallops which can be caught are under control of the quota management system.