National Control Plan for Northern Pacific Seastar (Asterias amurensis)
Implementation Workshop summary
Department of the Environment and Heritage, May 2002
In 2000 Australian Government's agreed to the National Control Plan for the Introduced Marine Pest: Northern Pacific Seastar (Asterias amurensis).
A May 2002 workshop aimed to improve the targeting of current efforts to implement the Control Plan. Workshop invitees included representatives of key marine industries, and State and Commonwealth agencies and representatives from New Zealand.
Workshop background papers outlined key aspects of the Control Plan including area at threat, the environmental and economic impacts to date and the implications for Australia's southern ocean shelf waters and maritime industries. Other key issues addressed included the range of regulatory tools presently available for controlling the spread of the seastar and overviews of current research projects directly relevant to the control plan.
Workshop participants recognised that priority should be given to measures that prevent the North Pacific Seastar introductions to new areas across Southern Australia. Various preventative techniques are already available, and their application provides an immediate and more certain return on investment and also circumvents the considerable economic and environmental cost and uncertainty of seeking to control established populations, given that control options have yet to be developed.
The Centre for Research into Introduced Marine Pests (CRIMP) provided an overview of a management simulation model that was being developed to control the spread of the seastar in southern Australian waters. The full outcomes of the model will be available in one to two years, but key outcomes will be implemented as the model is being developed. To assist in the development of the model, participants identified and ranked vectors of the seastar and then identified key actions that would prevent its spread from infected Australian sites. This preliminary hazard analysis identified major vectors and actions required immediately, to prevent the spread of the seastar.
The preliminary hazard analysis identified nineteen vector groups, which were then characterised and ranked according to six attributes, such as the relative range and volume of a vector group. Seastar larvae and non-larvae, which include both adults and juveniles, were assessed separately as the behaviour of each of these life-stages is markedly different. Larvae occupy the water column until they settle juveniles and grow into adults.
Consideration of the hazard analysis led to the following actions being recommended:
- Ensure the legislative and associated regulatory framework(s) across southern Australia are commensurate with the risk posed by the North Pacific seastar and that they fully support necessary management actions
- Ballast water was identified as the primary vector for spreading Asterias larvae. It was recommended that ballast water taken up in Port Phillip Bay or the Derwent River Estuary and the contiguous area of Storm Bay should be considered hazardous if it is proposed to be discharge to other Australian temperate ports. At this time and for the immediately foreseeable future, options to manage this hazard are limited to combination of the following
- Avoiding uptake of ballast water containing larvae (either by taking up ballast water in areas outside the above), or
- Taking up ballast only at times when larvae are not present in the water column
- Not discharge contaminated ballast water, in the destination port or other waters where there is risk of recruitment through larval survival. This could be achieved by exchanging ballast water in safe areas or disinfecting ballast water.
- Commercial fishing then mariculture equipment was ranked as the primary vectors for spreading adult seastars in southern Australian waters. It was agreed that industry adoption of improved practices is likely to lead to significant reductions in the risk of spreading the seastar. Risk reduction strategies include extension programs to improve the uptake of existing knowledge and improved understanding of the character of risks associated with particular fishing activities and vessel movements. The latter being required as the hazard is not consistently high for all fishing techniques and locations.
- The movement mariculture gear that has been deployed in areas affected by the North Pacific seastar requires explicit consideration in accordance with the National Policy for the Translocation of Live Aquatic Biota.
- While infrequent, oilrigs and barges were recognised as potentially important vectors for spreading the North Pacific seastar because of their long-range movements. Given the uncertainty in the operation of these vectors and the way that these vessels could become infected the assistance of these industry sectors should be sought to minimise the risk of spreading the seastar.