Soft-shell clam

​​In 2018 t​he Department of Primary Industries, Parks, Water and Environment (DPIPWE, now known as NRE Tas) detected the invasive marine pest 'soft-shell clam' (Mya japonica). Populations of clams have been found in the Prosser River at Orford and also the northern aspect of Spring Bay.

Soft-shell clams are large marine bivalve molluscs that bury themselves beneath the surface of the seabed. They are native to the northern hemisphere and have not previously been detected in Australia or other parts of the southern hemisphere. Genetic sequencing of specimens collected from the Prosser River confirmed them to be Mya japonica, a species originating from the northern Pacific region.

Soft-shell clams can grow up to 150 mm and typically live in sand, mud and gravel in shallow sub-tidal and intertidal zones. The clam exists beneath the soil surface burying itself up to 50 cm deep. It uses long siphons which pump water for respiration, feeding and spawning.

The clams are considered an invasive species of concern due to their potential to outcompete native species for habitat. Mya japonica present a potential pest risk to other areas of Tasmania and mainland Australia through the spread of larvae on water currents, or within ballast water. However, clams are most likely to be spread by people moving adults to new areas where they may spawn.

Further information on soft-shell clams may be found on the Australian Government website:

Marine Pests - Soft shell or long-necked clam

It is very important that the clams are not collected or moved to other locations.

Taking and possessing soft-shell clams prohibited

Following the recent detection of soft-shell clam, and in accordance with Section 270 of the Living Marine Resources Management Act 1995, Fisheries (Biosecurity) Order 2018 No. 2 was published in the Tasmanian Government Gazette (page 465) on 11 July 2018.

The Order formally prohibits the taking and possession of soft-shell clams in Tasmania by any unauthorised persons. The Order has been issued to control and prevent the spread of soft-shell clams (Mya japonica) within areas of Tasmanian State waters or to interstate regions.

Anyone finding what they suspect to be a soft-shell clam are encouraged to contact DPIPWE on telephone 6165 3777 or email:​ (supplying a photograph of the suspect clam will assist in identification).

Mya japonica - soft-shell clam - top view - copyright: TMAG

Mya japonica - soft-shell clam - base view - copyright: TMAG

Mya japonica - soft-shell clam - close ups - copyright: TMAG


Invasive Species Branch