Dredging for pest mussels complete in Tasman Bay
20 May 2008
A dredging operation to reduce the threat of exotic brown mussels establishing in Tasman Bay has been wound up, with MAF Biosecurity New Zealand (MAFBNZ) satisfied any remaining risk is minimal.
The dredging was in response to the discovery of live mussels (mostly the New Zealand green lipped mussel and the blue mussel, but also some small numbers of the invasive South African brown mussel Perna perna) on the area of seabed beneath where an oil rig was cleaned late last year.
Over recent weeks, two separate sites have been dredged by a scallop dredge, resulting in more than 50 tonnes of debris being pulled up and disposed of at a local landfill. The vast majority of the debris retrieved was material defouled from the oil rig, dead shell and sediment.
MAFBNZ Incursion Response Manager David Yard says from the outset, the risk of the small number of brown mussels present establishing a population in the area was low.
"We were, however, concerned that there was still some risk present, and undertook all practical measures to mitigate that risk," Mr Yard says.
Throughout the dredging process, there were steadily declining numbers of mussels present in the dredge debris retrieved.
"We can now safely say that we are comfortable all reasonable efforts have been made to eradicate the brown mussel, Perna perna, from the affected area in Tasman Bay.
"We have undertaken the best possible remedial measures in this situation and are confident any risk of establishment of P. perna from the oil rig defouling has been reduced to a negligible level."
The owners of the oil rig are covering the cost of the dredging clean up which stands at approximately $250,000.
A meeting to discuss the decision with key stakeholders in the Nelson/Marlborough/Tasman area is being planned for sometime in the next two weeks.
For further information, please contact:
- Lesley Patston, Senior Communications Adviser, Ph. 029 8940163