Suminoe oyster

• Suminoe oyster is a fast growing, large rock oyster belonging to the Ostreidae family of salt-water bivalve molluscs.
• It is large and flat in appearance and the shell can grow to up to 240mm long.
• Colours of the lamellae on the outer surface vary from grey and yellowish, brown to purple, while the inner surface of the valves is smooth and greyish- white, with purple on the edges.
• It has unequal valves and an irregular shape.
• Suminoe oysters are difficult to identify in the field from other species of native rock oysters, until they grow to a size larger than other species.
• The muscle scar on the inner surface of the valves is large and purplish.
• The internal shell lacks chomata (small ridges on the inside of the shell around its margin).
• Very similar in appearance to the black scar oyster (Magallana bilineata), another introduced marine pest found in north Queensland.

• The Suminoe oyster can grow attached to hard objects in brackish shallow intertidal or subtidal waters, as well as muddy creeks of warm estuaries.

• Has been detected at Bribie Island (Moreton Bay) and Brisbane (Boggy Creek, Pinkenba, and Kedron Brook).
• It is thought to be native to the coasts of China, but was introduced very early to Arakie Bay, in southern Japan and is also known from India and Pakistan and possibly Malaysia and Borneo.

• Females release eggs, and males release sperm, into the water column, where fertilization occurs.
• Spawning is related to water temperature and salinity and occurs at a bottom water temperature of 22–26°C.
• Suminoe oysters can reach sexual maturity in 2–3 months at a size of 40–60mm.
• Is a protandric hermaphrodite, maturing first as a male, and often becoming female in subsequent seasons.
• Fertilized eggs develop first into a ciliated trochophore larva, and then into a shelled veliger larva. The larva feeds on phytoplankton, and grows, eventually developing a foot and becoming a pediveliger, competent for settlement after approximately 14 days.

• The Suminoe oyster can foul submerged and floating infrastructure including pylons, pontoons and boats with the ability to occupy disturbed habitats including shallow subtidal sites and muddy creeks. However, little is known about the potential invasiveness and impacts.
• Biosecurity Queensland continues to investigate the extent of the incursions, which may inform future control, monitoring, or treatment measures.

Environmental

• Competes with native species for space.
• May carry exotic diseases and parasites.

Economic

• Fouling of wharf pylons, pontoons, marinas and marine aquaculture farms.
• Potential introduction of disease or parasites to commercial oyster farms.

• Feasibility of targeted treatment options are being assessed, however, the oysters are not able to be distinguished from native rock oysters in the field until they reach their distinctive large size, making selective treatment potentially unviable.
• Slipway operators, vessel inspectors and vessel owners should regularly and thoroughly check and clean vessel hulls, looking out for the pests. Pay particular attention to the nooks and crannies of vessels including internal seawater systems.
• Inspect, clean and dry equipment and gear before moving to a different location. This includes pots, nets, fishing or diving gear, anchors, and ropes.
• If you think you have seen Suminoe oysters, take a photo if safe to do so, record the location and report it online or contact us online, by phone or in person.

• Suminoe oysters are considered biosecurity matter under the Biosecurity Act 2014.
• By law, everyone has a general biosecurity obligation (GBO) to take all reasonable and practical measures to prevent or minimise the risk of Suminoe oysters spreading.