Protecting subantarctic islands from invasive species

NIWA is helping the Department of Conservation to ensure cruise ships don’t inadvertently carry unwanted foreign organisms on their hulls to New Zealand’s subantarctic islands.

DOC manages the marine coastal areas of the subantarctic islands and, in an effort to protect their high ecological value, requires a certain level of hull cleanliness before vessels are permitted to visit the islands. Currently, if vessels have anything more than slime fouling, they fail to meet permit requirements. Skippers are then faced with three options:

  • have the hull cleaned in dry dock
  • have the hull cleaned in water
  • get another detailed inspection carried out by a science provider, and a full risk assessment.


The first two options aren’t generally practical, so the only viable option is to get a risk assessment done, says NIWA scientist Dr Oli Floerl.

NIWA recently carried out biosecurity risk assessments on two vessels destined for the sub-Antarctic that had failed their initial inspection. This involved rapidly identifying specimens collected from the hulls and determining whether or not they posed a risk to the native ecology of the islands.

NIWA scientists were able to complete the risk assessment for Clipper Odyssey within 24 hours, causing minimum disruption to the vessel’s voyage schedule. Dr Serena Wilkens, of NIWA's Marine Invasive Taxonomic Service (MITS), provided preliminary on-site specimen IDs, which were subsequently verified by Dr Shane Ahyong (MITS), who studied pictures of the specimens emailed by mobile phone. A preliminary risk assessment suggested that those organisms which weren’t already established in the subantarctic would be unlikely to survive in the subantarctic because they came from the tropics. DOC made the final decision, giving the vessel clearance.

We are now working with DOC to develop:

  • rigorous hull inspection protocols
  • a biosecurity risk assessment framework
  • a decision tool to assist them in determining whether a vessel poses an acceptable or unacceptable level of biosecurity risk.

Contact: Dr Oli Floerl