Black-striped mussel

What is it?

Black-striped mussels (Mytilopsis sallei) are rapidly growing marine pests that breed quickly, fouling marine structures, vessel cooling systems and hulls and overgrowing other marine species. They are perhaps the most serious threat to tropical Australian waters.

Where is it found?

Native to the tropical and subtropical waters of the eastern Pacific, the Gulf of Mexico and northern parts of South America, black striped mussels have now spread to Fiji, India, Japan, Taiwan and Hong Kong.

They have the potential to infest Australia from Fremantle in Western Australia across the north of the continent to Sydney, as well as warmer parts of the Spencer and St Vincent Gulfs in South Australia.

What are its effects?

Black striped mussels live up to two years and grow to about 2.5 centimetres long in around six months, but need only be half this size to begin breeding. Each mussel releases tens of thousands of eggs and can spawn every 28 days.

Mussels spread rapidly over objects in the water, covering them and building a layer up to 15 centimetres thick. They foul anchors, pylons, buoys, stormwater pipes, vessel hulls and breakwaters and compete with native marine species for food and space, leading to a substantial reduction in biodiversity.

What’s the risk to Australia?

Black striped mussels invaded Darwin Harbour in 1998-99. Fortunately, the incursion was limited to an enclosed marina but eradication required pumping copper sulphate and chlorine into the infested site.

The emergency response required national and local action at great economic and social costs, though these were minor when compared with potential damage to a $350 million a year pearling industry and a northern prawn fishery catch worth close to $120 million.

In the Great Lakes region of North America the zebra mussel, a relative of the black-striped mussel, costs an estimated $US600 million a year in remedial engineering and in cleaning mussel encrusted pipes and water systems.

Transportation of black-striped mussels around the world has been linked with vessel hull fouling, and larvae could also be carried in ballast water.

AQIS has strict regulations regarding the berthing of vessels in Australian waters and, with few exceptions, requires vessels to conduct a mid-ocean exchange of ballast water en route to Australia to minimise the risk of introducing pests such as black striped mussels.