Sea trials for Atlantic salmon gill disease vaccine

The vaccine targets amoebic gill disease (AGD), a health problem that costs the Tasmanian industry some A$20 million a year in treatment and lost productivity, and is a major constraint to industry expansion.

“AGD is caused by amoebae that attach to the gills of Atlantic salmon,” says CSIRO scientist, Dr Mathew Cook. “The affected fish are safe to eat, but lose condition and must be regularly bathed in fresh water to detach the amoebae.”

The sea trial is the third phase of an industry-backed vaccine research project led by CSIRO through the Food Futures Flagship and funded by the Aquafin and Australian Seafood Cooperative Research Centres (CRCs) and the Fisheries Research and Development Corporation.

Initiated in June 2002 by Aquafin CRC, the first phase of the project identified genes in the infective amoeba likely to trigger an immune response in the fish. Those genes were then used to produce a vaccine.

In the second phase, laboratory trials conducted in collaboration with the University of Tasmania indicated the vaccine provided a 40 per cent increase in protection against AGD.

In the sea trial, to begin in late August, three thousand Atlantic salmon will be grown by Huon Aquaculture Company at its Hideaway Bay marine farm in the Huon estuary. The salmon were bred by Salmon Enterprises of Tasmania at Wayatinah in the state’s Central Highlands and have been electronically tagged for identification.

Half of the salmon have been vaccinated, and the other half treated with a ‘control’ injection not containing the vaccine. All will be regularly assessed for the presence of gill amoebae during spring and summer.

Huon Aquaculture Company director, Peter Bender, says the vaccine offers a positive management tool to address one of the industry’s major health challenges.

“An effective vaccine would improve fish welfare through summer, reduce or eliminate the need for fresh-water bathing, and potentially improve salmon growth rates, making Tasmanian salmon more cost-competitive in the global market,” Mr Bender says.

Dr Cook says the project is unique in attempting to vaccinate against an external parasite in fish. He says the focus going forward lies in translating the laboratory results into the field where the infection is very different.

“In the laboratory, AGD is an acute infection, but in the field it’s more chronic,” he says. “So we may just have a vaccine that protects against an acute challenge. Our real measure of success will be the level of reduction in fresh-water bathing.”

Downloadable images are available at: Sea trials for Atlantic salmon gill disease vaccine