Preliminary results show that infection trials in RAS facilities can be conducted faster than in flow-through systems.
Infection models are important tools in fish health research, and must resemble real conditions in aquaculture operations as much as possible. Nofima has many years of experience in establishing and using infection models in flow-through systems. Currently, RAS facilities dominate salmon production, and infection models must be reassessed and adapted to RAS.
In collaboration with Tromsø Aquaculture Research Station and UiT – The Arctic University of Norway, Nofima has established brand new RAS facilities. Recently, the first infection trials were carried out there by Nofima. The conclusion after the first experiments is that the infection models worked very well and that the RAS trials can be carried out in less time compared to trials conducted in flow-through systems.
Disinfection strategies have played a key role in the trials that have taken place so far. It is crucial to establish protocols for the disinfection of RAS facilities, and for how any disease outbreak should be managed.
“In the RAS trials, we have simulated, among other things, how pathogenic bacteria get into the RAS facilities. This allows us to study how disease develops in the fish, while at the same time we can investigate how and where the pathogens establish themselves and spread throughout the system”, says Carlo C. Lazado, senior scientist at Nofima.
The new RAS facilities for infection trials will provide more relevant knowledge for the industry about what happens when infection enters RAS facilities, and how this can be managed through both treatment and prevention, says fish health scientist at Nofima, Lill-Heidi Johansen. Photo: Lars-Åke Andersen/Nofima.
In previous reports, Nofima has pointed out that many RAS facilities in Norway and North America have disinfection protocols, but it is uncertain how effective these are if pathogens such as viruses and bacteria enter the system.
“Several trials conducted in the new RAS facility will provide us with knowledge about critical areas in the system where the pathogens potentially thrive. This knowledge will be crucial for us in developing risk assessment protocols in RAS, but even more importantly, in developing disinfection protocols that are effective following a disease outbreak”, says Lazado.
A more rapid course of disease
The RAS facility in Tromsø is the first of its kind where it has been reported that this type of controlled bacterial infection trial on salmon has been carried out.
“When we recently conducted a trial with the pathogen Yersinia ruckeri, we saw that disease developed faster than in flow-through systems. The fish were also susceptible to experimental infection at a different stage in the production cycle compared to what we have observed before. This provides more flexibility in infection trials. In addition, we will test virus infection in the system to see if the same tendencies are observed”, says Lill-Heidi Johansen, fish health scientist at Nofima.