Marine Pests 

What is a Marine Pest?

Marine pests are non-indigenous plants or animals that have a significant detrimental impact on the marine environment. They may threaten the biodiversity and abundance of native species, or they may adversely impact on commercial and recreational marine industries such as fisheries, tourism, aquaculture and port industries.

Marine pests can include mussels, fish, sea stars, crabs, sponges, algae, and various other marine species.

Most marine pests are introduced from vessels arriving from overseas. However, not all are from outside of Australia, and some may be species native to other regions in Australia, but which have been translocated via domestic shipping or the aquarium trade to locations outside of their normal range.

How do marine pests get here?

Marine pests are great hitchhikers. They can be spread via internal seawater systems on boats, such as inside pipes, or in ballast and bilge water. They may be introduced by attaching to boat hulls, or on anchor chains, fishing gear, and other recreational equipment. They may also be introduced as aquaculture species or via the aquarium trade.

Marine pest problems

Marine pests pose both ecological and economic threats. Once established, pests can wreak havoc with natural aquatic ecosystems, competing with, preying upon, and displacing native species and modifying their habitats.

Marine pests can also cause considerable damage to structures and vessels. Marine pests foul the hulls and seawater systems of boats which can reduce speed and increase fuel use. Marine pests can also clog cooling water intakes resulting in overheating and damage to boat motors.

In March 1999 the black striped mussel was detected in plague proportions in Darwin marinas. The threat to commercial and recreational fishing, aquaculture, tourism and port industries of northern Australia resulted in $2.2 million being spent to eradicate the pest species.

What are we doing to stop them?

International boats intending to enter Darwin marinas must pass a hull inspection and undergo treatment of their seawater systems.

Aquatic Biosecurity incorporates a monitoring component which documents water quality, and records the presence or absence of aquatic pests in Darwin Harbour and it's marinas, as well as in Gove Harbour, Melville Island and Groote Eylandt. The monitoring program also involves the collection of artificial settlement plates from collectors distributed in these areas where there is a large volume of vessel traffic. The detachable plates are collected on a regular basis and examined for the presence of aquatic pests.

The Aquatic Biosecurity unit also works closely with Indigenous Sea Ranger Groups around the Northern Territory so as to enhance community awareness of marine pests, and also to expand the area currently being monitored and utilising local knowledge of remote areas that may be susceptible to pest incursions.

What you can do to help?

• Regularly clean and check seawater systems on your boat.
• Keep clean and antifoul the hull of your boat every year.
• When cleaning your vessel or any gear, make sure that NO debris (including any organisms) is allowed to return to the water, so as to reduce the risk of introducing non-indigenous species.
• When out fishing, diving or boating, report any unusual aquatic growth or aquatic life in unnaturally high numbers.

Related Information

• Aquatic Pest Eradications - Black Striped Mussel 
• Exotic Marine Pests 

For factsheets and information on marine pests, visit the Resources page.