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Marine pests

What are marine pests?

Marine pests are highly invasive animals and plants from other parts of the world that have become established in Victoria and cause significant harm to the health of marine ecosystems. Many of these invaders arrived in Victoria accidentally, as larvae in ballast water or as adult hitch-hikers on ships that visit the port.

At least 250 marine species of both animals and plants are known to have been introduced to Australia's marine waters and over 100 species introduced to Port Phillip Bay. It is important to note that not every introduced species will become a pest.

Pest species cause harm by competition with native species for space, light, or food, or by preying on native species. Pests often breed quickly and produce large numbers of offspring which often gives them a competitive advantage over native species.

Some native species can also become pests if they begin to cause harm to the environment. For example, the native Black-Spined Sea Urchin (Centrostephanus rogersii) has caused loss of extensive kelp forests in south eastern Australia as a result of loss of their predators and warming seas. Native species extending their range further south into Victoria as a result of climate change will also pose an ongoing concern to marine ecosystems.

What is at stake?

Over 90% of plants and animals living in Australia's southern waters are found nowhere else in the world.

Pests can seriously affect habitats, food chains, the ecosystem and our enjoyment of the marine environment. Some marine pests are also a risk to human health and affect the social and economic benefits provided by the marine environment including aquaculture, recreational and commercial fishing and domestic and international shipping.

Port Phillip is a major international port and is an entry point for new marine species into Victoria. Consequently, there are many exotic species found in the bay. In recent years however there have been reports of marine pests outside of Port Phillip including at Apollo Bay (Wakame), San Remo, Inverloch, Tidal River, Gippsland Lakes (Northern Pacific Seastar), and Western Port (Pacific Oysters).

Preventing the spread of pests is a key challenge for all responsible agencies and the community. Once a pest becomes established, it is nearly impossible to eradicate.

Marine pest species in Victoria

The most concerning marine pest species in Victoria include:

  • Northern Pacific Seastar - Asterias amurensis
  • Wakame - Undaria pinnatifida
  • Pacific Oyster - Crassostrea gigas
  • Green Shore Crab – Carcinus maenus
  • European Fan Worm - Sabella spallanzanii
  • New Zealand Screw Shell – Maoricolpus roseus

Parks Victoria has developed a guide to assist people to identify pest species:

Further information on identification and biology of marine pest species can be found at from the National Introduced Marine Pest Information System (NIMPIS).

Reporting marine pests in Victoria

People who spend time on the water or visit the coast can provide early warning of new marine pests or the spread of existing pests.

If you suspect you have seen a marine pest not currently known to the location please report your sighting to

Reports should include:

  • A clear photograph, preferably with a scale (e.g. shoe, coin or pen) to show the size of the pest
  • The date and time of the sighting
  • The location of where it was found (e.g. a marked map, GPS coordinates)
  • Contact details to follow up for further information about the sighting.

Suspected sighting of marine pests should be reported to DEDJTR on 136 186 or to

Please do not collect or remove suspected marine pests. Some native species can easily be mistaken for pests.

What can I do to prevent the spread of marine pests?

Marine pests are spread by both natural means and with human help. Moving vessels and marine equipment from areas with marine pests, such as Port Phillip Bay, to new locations can significantly increase the risk of spread.

To help prevent the spread of marine pests practice the check, clean, dry approach:

  • Check your vessel and any marine equipment for marine pests
  • Clean with fresh water to eliminate pests at juvenile growth stages that are invisible to the eye
  • Dry boats and marine equipment thoroughly before moving to other areas, especially from Port Phillip Bay to other parts of Victorian coast
  • Regularly apply appropriate anti-fouling paints to vessel hulls according to manufacturer instructions
  • Never use marine pests as bait

Marine equipment includes any objects that get immersed in water, including: boats, other watercraft, fishing gear, ropes, buckets, wetsuits and water toys.

See Parks Victoria’s guide for recreational boaters below for more information.

Check, clean, dry. Stop the spread of marine pest