IMMERSION VACCINATION

Method

Salmon are placed in a container filled with a solution of vaccine (EFSA, 2008) or they can be sprayed by the vaccine (Press and Lillehaug, 1995). The chemical agent will diffuse through the skin barrier or taken up by the gills.

Salmon being immersed into a container full of vaccine solution.

Welfare Concerns

• Immersion vaccination exposes the salmon to air for some period of time which may induce stress.
• Not as effective as the injection method in eliciting a humoral response and the duration of protection conferred by immersion vaccination is less.

Welfare Benefits

• No physical penetration by a needle is required thus eliminating any chance of local reactions, spinal deformities, intra-abdominal distortion or lesions, and granulomata

Economic Concerns

• Relatively weak strength and duration of immunity provided by vaccine meaning this method is not commonly used although it is more welfare considerate relative to the injection procedure; the costs outweigh the short term immunity
• Excess amount of vaccine is required since salmon vaccine uptake is low and time consuming relative to injection vaccination, adding to production costs