Marine pests in Victoria

Marine pests are highly invasive, non-native animals and plants that can cause significant harm to Victoria's marine environment. These pests can include a wide range of organisms, from microscopic algae to various species of:

  • sea stars
  • seaweed
  • fish
  • barnacles
  • sea squirts
  • mussels
  • crabs.

Where marine pests come from

Marine pests can arrive into Victoria from other parts of the world or even other Australian waters. Many of these invaders can arrive:

  • accidentally through the aquarium trade
  • as unwanted tourists attached to the hulls of ships that visit our ports, or
  • as larvae in ballast water.

Learn more about how you can reduce the spread of marine pests.

Why marine pests are a problem

Pests are a problem for the following reasons:

  • Once introduced, marine pests reproduce quickly, often producing large numbers of offspring that can rapidly spread to new areas.
  • They compete with native species by preying upon them, and outcompeting them for space, light, food, or overgrowing them.
  • They can also introduce diseases and parasites to our native species, and clog internal pipework resulting in overheating and damage to boat motors.

Because of their invasive nature, marine pests pose a significant threat to our marine biodiversity and economy. Once marine pests become established, it is nearly impossible to eradicate them.

The current situation

Australia has over 400 introduced and cryptogenic (unknown origin) marine species, including plants, animals and algae. In Victoria, Port Phillip Bay has at least 100 confirmed records of introduced and 61 cryptogenic marine pests, although some estimates put the number at more than 300.

Everyone can play a part in reducing the introduction and spread of marine pests. If you think you've found a marine pest not currently known to the location, report your sighting to

Agriculture Victoria has developed an Invasive Marine Pests Module under the Victorian Government’s Invasive Plants and Animals Policy Framework (IPAPF). The module sets out the Victorian Government’s approach to the prevention, eradication, and containment of marine pests and protection of assets from marine pests. The Invasive Marine Pests Module and more information on the IPAPF can be found on the Invasive Plants and Animals Policy Framework page.

More information

Search Victoria's Marine Pest Deck or the National Introduced Marine Pest Information System for information about specific pests.

Or see these pages:

Organisations and regulators:

Page last updated: 07 Mar 2024