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Bay Dredge Hopes to Halt Invasion

by Ellen Hardy
28 February 2008, at 12:00am

TASMAN BAY - The clean down of an oil drilling rig has been blamed for the arrival of an invasive mussel species in the Tasman Bay. However, the company which caused the problem has put up $85,000 to cover the cost of dredging work which is about to be carried out in an attempt to contain a potentially harmful species.

New Zealand Biosecurity, which has helped organise the clean up operation, said that South African mussels had been found on 8 December 2007 at the site where the semi-submersible drilling ship 'Ocean Patriot' had been defouled. The ship was 22km offshore and cleaning off New Zealand greenshell mussels, by order of the Victorian state government, before it was towed to Australia.

NZ mussel farmers in the region were alerted about the potential spread of South African brown mussels from the bay. A warning has now been issued about spawning as this species could present serious consequences for New Zealand's $200 million greenshell mussel industry.

Prime Aquaculture at Risk

Tasman Bay and nearby Golden Bay are key aquaculture areas, producing 20 per cent of the industry's mussel spat. The Ministry of Agriculture and Forestry has asked oyster fishers for a 2km "exclusion zone" around the site until the dredging is done on Monday and Tuesday.

MAF's biosecurity incursion response manager David Yard said a 700sq m area of seabed, including a 300sq m buffer area, would be dredged. The dredging would be managed by Nelson's Cawthron Institute.

Ellen Hardy