Drilling Rig Adventure Provides Valuable Biosecurity Insights.

The recent biosecurity inspection of the semi-submersible drilling rig, Ocean Patriot, for marine pest species is a world first and has provided valuable knowledge to Cawthron scientists, MAF Biosecurity New Zealand (BNZ) and the oil industry.  Victorian government authorities had requested that the rig owners carry out the inspection prior to its arrival in Australia, and they called in Cawthron’s biosecurity experts to undertake the survey off the coast of New Plymouth.

Project leader, Grant Hopkins says it had to be a fast job.  “They gave us a team of 14 divers as well as a remotely-operated vehicle.  The lost production costs on a rig like that are enormous so it was about being fast and accurate”.  The list of species they were looking for included our own GreenshellTM mussel, which Australia doesn’t want.  A survey was also taken at this time for BNZ to determine what other species were present on the oil rig.  Within ten minutes of the survey starting GreenshellTM mussels were found and the focus then switched to de-fouling the rig.  The Ocean Patriot was towed to a more sheltered site off Tasman Bay and 1200 psi underwater water-blasters and handheld scrapers were used to clean the rig structure.

After cleaning of the oil rig it was revealed there were also species of organisms present that New Zealand didn’t want, such as the brown mussel (Perna perna) from South Africa.  BNZ then required a clean up of the seabed beneath the rig to reduce the risk of Perna perna establishing in the area.  Grant says that “using specialised sonar equipment Cawthron identified the exact location of the de-fouled material and a dredging programme has begun to physically remove this biosecurity threat”.  This project will contribute significantly to our knowledge about biosecurity risks posed by oil rigs and similar structures, which will ultimately improve the way in which New Zealand manages these risks in the future”.