European Shore Crab (Carcinus maenas) - Invasive Species
The Department of Fisheries is working with the community to manage and conserve Western Australia's fish and aquatic habitats. An important part of this work is protecting our environment and fishing industry against introduced plants, animals and diseases which pose a serious threat to the State's aquatic environment.
WA is free from many of the introduced species that are found in other areas of Australia and overseas, but we will only enjoy this status as long as we maintain a vigilant lookout for these invaders.
Industries such as tourism, aquaculture, recreational and commercial fishing are dependent on the natural diversity that occurs within our marine ecosystem. Nobody benefits from the introduction of invasive species – especially the environment.
Early detection is vital to the successful eradication of this species. Eradication of even small infestations has proven to be expensive and at times impossible in certain conditions. Eradication and control measures are likely to impact on both commercial and recreational activities. The environmental impact is likely to be severe.
What is a European Shore Crab
The European shore crab (Carcinus maenas) is a small crab that is sometimes referred to as the green crab. Adults measure a maximum of 8cm across and the shell (carapace) colour varies, but is usually dark greenish with yellow markings. Sometimes they may be bright orange underneath. The crab has five distinct spines on the outside edge of the carapace on either side of the eyes.
The European shore crab is a highly adaptable invasive species. It has established populations outside of its native range, including South Africa and North America. The species was first found in Australia (New South Wales, Victoria and South Australia) in the early 1900s and more recently it was discovered in Tasmania.
While preferring bays and estuaries it may be found on all types of shore from the high water mark to depths of 60 metres. However, it is predominantly a shore and shallow water species. It can tolerate a wide range of temperatures (5 to 30 degrees) and salinities (5 to 33 parts per thousand). The European shore crab is a voracious predator with a diet that includes a variety of animals and plants including mussels, crabs and fish.
What You Can Do
There are several things you can do to help avoid the establishment of the European shore crab in Western Australia.
Recreational fishers:
- After any fishing trip, inspect your gear to ensure it is not harbouring any aquatic species. This will reduce the risk of translocating aquatic species between fishing locations within and across the states and territories.
Scuba divers:
- After diving inspect all of your diving equipment to ensure it is not harbouring any aquatic species. This will reduce the risk of translocating aquatic species between dive sites within and across the states and territories and when returning from international dive locations.
Boat owners:
- Remove any pieces of seaweed and other aquatic species from anchors, ropes, chains, bait buckets and boat wells, that may harbour and aid the further spread of aquatic species to other areas.
- Ensure appropriate antifouling paint applications are maintained to reduce the settlement and growth of fouling species. This will not only increase fuel economy, but is likely to further reduce the spread of any fouling aquatic species.
Reporting Introduced Species
While in or around any Western Australian aquatic environment, be aware of your surroundings. If you suspect you have identified European shore crab or any other possible introduced species within WA, please contact the Department of Fisheries' FISHWATCH service on 1800 815 507 or contact the Department's Translocation Officer on (08) 9482 7385.
For further information contact the Department of Fisheries.
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