Pests

Our reporting considers non-native invasive species - animals and plants. We know they can cause significant harm to Victoria's marine environment.

In fact, their spread is one of the most threatening processes contributing to global biodiversity loss. Monitoring is critical to determine whether their range is expanding. New incursions require rapid management responses.

Marine species are most commonly introduced and spread by ballast water and biofouling. Ballast water is taken on board by vessels to maintain stability and trim. It can contain thousands of aquatic microbes, plants and animals which can spread across the globe when released. Vessel biofouling happens when marine plants and animals grow on the submerged parts of a vessel or infrastructure.

Port Phillip Bay

There are now more than 160 invasive marine species present in Port Phillip Bay. The impacts of some of these species is significant. The northern Pacific seastar has been shown to cause changes in fish populations in Port Phillip Bay. New invasive species continue to arrive in Port Phillip Bay, most recently the Asian shore crab. This species was first detected at Mount Martha on the Mornington Peninsula in late 2020.

Western Port

There are several known invasive marine species in Western Port. However, the sizes and number of infestations are significantly less than in Port Phillip Bay.

Corner Inlet and Nooramunga

Corner Inlet has remained relatively free of invasive marine species. However, Japanese kelp has been detected at Port Welshpool. The northern Pacific seastar has previously been detected at nearby Tidal River as well.

Gippsland Lakes

The northern Pacific seastar was first detected in the Gippsland Lakes in 2015 and spotted again in 2019. Both detections resulted in surveillance and removal activities. The species is extremely difficult to eradicate and can rapidly establish large populations in new areas.

Pest management

The detection, monitoring and management of invasive plants is a complex and important process. It is vital to ensure the adverse effects of invasive plants are minimised. The State of the Yarra and its Parklands 2018 Report reported on impacts from weeds and pest animals along the Victorian coastline. These findings are presented in Part III of our report. We also analyse datasets developed by the Department of Environment, Land, Water and Planning (DELWP) and the Department of Jobs, Precincts and Regions (DJPR).

The management and coordination of marine pest management across agencies remains a challenge. It is especially difficult once pests become established in the state and are no longer a biosecurity issue managed by DJPR. An end-to-end pest management plan is required to cover the full invasion curve from prevention and preparedness through to on-ground asset-based management.

• To learn more view this case study on the prevention of marine pests, and what vessel owners can help stop the spread of marine pests by always remembering to check, clean and dry.

More information

• View the full indicator assessment table
• Explore case studies
• Download the State of the Marine and Coastal Environment 2021 Report and view the interpretive website for the report.