Intermittent, Continuous and Single Point Delivery of Stembiont by Bath and Concurrent Dip Administration together with IP Vaccines

Stembiont is a probiotic enhancement product that is used to seed fish with good bacteria to enhance the microbiome and improve robustness to reduce the impact of pathogenic ulcer bacteria on seawater rearing. The challenge on commercial farms is to find an appropriate point in the rearing cycle to administer. We have so far shown that bath, dip or concurrent administration in anesthetic bath is feasible and does not interfere with the immune response of the vaccine or with the viability of Stembiont or efficacy of the anesthetic. We have large scale field trials to determine the efficacy on the long term of Stembiont. The purpose of this study is to see if the nature of the vaccine used concurrently effects the persistence and biodistribution of the Stembiont seeding, and also, relative to the proposed use of Stembiont as a single point administration, if continuous or intermittent seeding such as would be possible on farm sites augments those attributes. The study will employ individually PIT tagged fish and a cohabitation in saltwater after initial seeding in FW (30 days). This will as much as possible minimize the tank effect and give high power to the study to study the weight gain on individual fish. It is expected that as the incoming water in the facility at NIVA is not preventing the influx of typically isolated uncreative bacteria so the infectious pressure on the system is a determinative factor in treatment efficacy. As a large component of the study will look a treatment and use indication for the effect on weight as tertiary factor, we will propose the study duration to be 6 months after sea-entry and 7.5 months duration in total, including the acclimatization period during which the fish will be PIT tagged, and the 30 day freshwater period where the dose will be administered. We will use 935 smolts (Salmo Salar) devided in 17 tanks. We will use the lowest number of individuals to give us statistically valued results. We can not see that this trial is possible to do without live animals, but the ones we do use will not undergo any harm or unnecessary stress.The treatment will cause minimal stress, dip will be done in their natural habitat, and IP vaccine will be administered under anasthesia. Biomass will be monitored and kept under recomended limit values. There will be minimal handling and handling and sampling will be done under anesthesia. The Fish will be tended, fed and monitored by a Fish Health Biologist. Any signs of moribund behaviour will lead to humane endpoint.