Asian shore crab

Asian shore crab (Hemigrapsus sanguineus, also known as Pacific crab or Japanese shore crab) an be distinguished by the spots on its claws and 3 spines either side of the eyes. It is only a small species of crab, approximately 4cm shell width. It can be found in estuarine and marine habitats.

The Asian shore crab is currently not recorded in Australia, but if introduced, has the potential to compete with and prey upon native fish, crab and shellfish species. It is listed as prohibited matter under the NSW Biosecurity Act 2015 may not be brought into NSW or released or allowed to escape into any waters in NSW. Recent detection of this species in Port Phillip Bay, Victoria makes this species one of particular concern for translocation into NSW.

Reporting

If you think you have seen an Asian shore crab in NSW, please take several clear, high resolution photos of the crab. For identification, we need to see the:

  1. top of the crab’s shell (carapace)
  2. spines either side of the eyes
  3. top of the crab’s claw
  4. pattern on crab’s legs

Including something for size reference, like a coin or note, is useful in determining the size of the crab from photos.

Please send the photos to Aquatic.Biosecurity@dpi.nsw.gov.au, along with details of when and where the crab was seen.

Identification

Key features:
  • Spots on claws
  • 3 spines either side of the eyes
  • Shell square up to 4cm wide
  • Shell varied colour green/purple to orange/brown
  • Banded pattern on legs
  • No indentation between the eyes
  • No hairs on legs
Known locations:
  • Detected in Port Phillip Bay, Victoria in January 2021
  • Not recorded elsewhere in Australia
Habitat:
  • Estuarine and marine habitats
  • Intertidal shallow hard-bottom areas including under rocks, shells, debris and artificial structures

Vectors:

  • Vessels
Impacts:
  • Broad diet, competes with and preys upon native species such as crabs and shellfish.
  • Potential impact on aquaculture production due to predation on commercially important scallops, mussels and oysters.
  • May also carry disease that could affect prawns, other crabs and lobsters.

A squarish shaped crab, orange to brown in colour showing spots on claws and banded pattern on legs.

Similar native species

These native species may be confused with this marine pest and do not need to be reported. But if unsure, take a photo and let us know.

Swift-footed crab (Leptograpsus variegatus)

Key features:

  • Dark-olive green to dark purple
  • Shell up to 8cm wide
  • Large front claws are purple with white tips
  • Three spines on either side of eyes

Known locations:

  • QLD, NSW, VIC, Tasmania
  • Is the most active and prominent crab on Sydney’s rocky coast.

Habitat:

  • Exposed intertidal rocky shores
A small olive green to purple swift-footed crab on a rocky shoreline

Smooth shore crab (Cyclograpsus audouinii)

Key features:

  • No spines around the edges of the shell
  • Smooth rounded shell up to 4cm wide
  • Varied colours from red brown/purple and yellow to purple, dark grey or brownish grey

Known locations:

  • From Hervey Bay QLD south through NSW, VIC, SA to Bunbury WA.
  • Under rocks on sheltered and moderately exposed shores
A varied colour crab (purple, yellow, dark grey) on a black background.

Sowrie (Plagusia glabra)

Key features:

  • Smooth shell green-brown colour
  • 4 distinct spines on either side of eyes
  • Walking legs have sharp spines on the ends for grasping rock.

Known locations:

  • From south-east QLD through NSW to the Victorian border

Habitat:

  • Low level rocks shores, preferring to sit at the bottom of rock pools or in cracks and crevices.
A small green-brown coloured crab on a rocky shore.

Spotted smooth shore crab or Mottled shore crab (Paragrapsus laevis)

Key features:

  • Shell width up to 4cm
  • 2 spines either side of eyes
  • Body yellow-brown with darker red patches
  • First set of legs felted with hairs
  • Gregarious species, often found in groups

Known locations:

  • South-eastern QLD down through NSW and VIC; also found in TAS.

Habitat:

  • Intertidal, sheltered coastal bays and estuaries
  • Rarely found in the open, prefers hiding under rocks, debris, in mangroves and in burrows on mudflats.
A small yellow-brown to dark red crab on a rocky surface