Case Study: Eradicating a small outbreak of the Northern Pacific Seastar
The search and eradication effort
Why choose eradication?
The eradication process
What has been achieved
World Environment Day Award winners
The search and eradication effort
| In late 2003 the first Northern Pacific Seastars were found in rock exposed at low tide just outside the entrance to Anderson's Inlet at Inverloch on northern Bass Strait. Victorian authorities were quickly alerted to the seastar’s presence by the local community, who played a key role in the emergency response. It was the first time a population of the seastar had been found on the Australian mainland outside of Port Phillip Bay and if allowed to establish, it was likely that the seastars would spread along the Victorian coastline and into New South Wales. |  |
Why choose eradication?
Prevention rather than cure is the best approach when it comes to managing marine pests. Only in unique circumstances will it be feasible to eradicate a marine pest outbreak. The outbreak at Inverloch was a unique situation and differed from many other outbreaks that are only detected after the pest has become well established.
The decision to attempt eradication of the seastar at Inverloch was therefore based on the following factors:
- The outbreak at Inverloch occurred in a single year and annual outbreaks at this location were unlikely.
- The Inverloch population had not reproduced so only adults were present.
- The outbreak was localised in a small area of 150m by 50m.
- Local conditions were suitable for divers to remove individual seastars by hand:
- It was possible for divers to remove ALL not just some of the seastars:
- The local community in and around Inverloch was committed to the effort.
The first step was finding out where the seastars were located. Over a number of weekends, divers started to systematically survey the region both inside and outside Anderson's Inlet.
Survey efforts were greatly assisted with footage taken via towed and remotely-operated underwater video cameras controlled by survey craft in the deeper waters off the Inlet and also benthic trawl surveys over the sandy seabed. Local knowledge and computer modelling of the water patterns in the region also played a big part in focusing search efforts.
In March 2004, an aggregation of seastars was detected just inside Andersons Inlet on a tidally affected sponge-covered reef. No other aggregations were found in the region.
Because of the characteristics of the outbreak at Inverloch, it was considered that eradication was feasible. The only real option was hand removal by divers. Although a daunting task, there was considerable support and commitment to mount an eradication response from local divers, the Inverloch community, Victorian Government and from relevant government agencies across Australia. The "Seastar 2004" team included:
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What has been achieved?
Surveys in the Andersons inlet in 2007 and 2008 have failed to collect any Northern Pacific Seastars. From this information, it is hoped that the rapid response of government and the local community in 2004 and 2005 has eradicated the infestation.
The efforts of the Seastar 2004 team have helped to raise the profile of the marine pest issue within the community and within the Australian media. This has highlighted not only the ‘pest problem’ but most importantly, the ‘pest solution’- that prevention is better than cure when it comes to stopping the spread of marine pests. Where a unique opportunity appears making eradication feasible, the efforts of the Seastar 2004 team have highlighted the level of resources and time that will be required in an eradication attempt.
These efforts have also helped to launch major initiatives dealing with risks from small vessels and ships ballast water. They support CSIRO developments of cutting edge molecular technology that allows for precise identification of marine pests in ways not thought possible a decade ago.
At a national level, the team's work has also been scrutinised by the national body established to deal with marine pest emergencies (Consultative Committee on Introduced Marine Pest Emergencies) and has set a new benchmark in responding to such incidents.
A debriefing of the emergency response to the outbreak was completed. The debriefing report highlights key issues raised, which will be addressed in future response planning.
Final Debrief Report Inverloch Incident (PDF - 148 Kb) Response area - Search and Eradication area for Northern Pacific Seastar (PDF - 467 Kb)World Environment Day Award Winners
Community efforts to eradicate the Northern Pacific Seastar at Inverloch received the top award in the United Nations Association of Australia World Environment Day Awards 2004. The "Seastar 2004" team of volunteers won the Community Category Award for Best Community Based Environmental Project or Initiative.
Congratulations to the Seastar 2004 Team on their efforts.
Read a summary of the award winning entry.
Diving in to help – the Northern Pacific Seastar at Inverloch (PDF - 12 Kb)DSE, other Government agencies and volunteers were also highly commended in the "Excellence in Marine and Coastal Management" category for their efforts in coordinating the response to the seastar search, which has set a new benchmark in incident response.
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