Action: Use vaccinations
- Two controlled studies from Iceland and Norway found higher survival rates in vaccinated salmon compared to unvaccinated control groups. This was post exposure to the disease-causing bacteria, Aeromonas salmonicida spp.achromogenes and Yersinia ruckeri, respectively.
- Two controlled studies in Australia and Canadia reported higher survival in salmon infected with marine flexibacteriosis and bacterial kidney disease, post vaccination.
- Two controlled studies in Norway reported similar results for salmon vaccinated against infectious salmon anaemia.
Atlantic salmon cultured in commercial farms are at an increased risk of contracting and transferring infectious bacterial diseases and other pathogens. Administering vaccinations that target specific infections aims to reduce or eliminate disease contraction which may spread within the salmon farm, from wild salmon to cultured salmon and vice versa.
Supporting evidence from individual studies
In 1997, a replicated, controlled study in Iceland (Gudmundsdottir and Gudmundsdottir, 1997) found that vaccinating salmon, Salmo salar, with IBOO improved survival rates of fingerlings when exposed to a disease-causing bacteria, Aeromonas salmonicida spp. achromogenes. After 16 days, the lowest level of mortality (51%) was observed in groups vaccinated with IBOO compared with the unvaccinated control groups (81% mortality). Infection with the bacteria leads to the development of furunculosis in salmon. Vaccines were made from A.salmonicida spp. achromogenes strain M108-91, furunculosis vaccine and an oil adjuvant. Salmon were exposed to A.salmonicida spp. achromogenes 70 days post vaccination.
In 2005, a replicated, controlled study in Norway (Mikalsen et al., 2005) found that the pEGFP-HE vaccine increased survival in salmon, Salmo salar, exposed to infectious salmon anaemia virus. Mortality levels in groups given the vaccine were lower than the unvaccinated control groups (16.3% and 25% versus 45% and 41.3%, respectively). Fingerling salmon were injected with a dose of a DNA vaccine expressing the virus. Dosage was repeated after week three and six. Three weeks after the final immunisation, salmon were exposed to infectious salmon anaemia virus and mortality levels were recorded for 54 days.
In 2007, a randomised, replicated, controlled study in Tasmania, Australia (van Gelderen et al., 2009) found vaccination against marine flexibacteriosis increased survival rates in salmon, Salmo salar. Salmon injected with a vaccine and adjuvant showed significantly lower mortality levels (11%) than a group given the vaccine only (39%), a group given the adjuvant only (54%) and an unvaccinated control group (50%). Four groups of salmon (32-38 individuals in each) were given different treatments: a vaccine against marine flexibacteriosis, a vaccine and an adjuvant, an adjuvant only and no injection. Salmon were exposed to marine flexibacteriosis eight weeks after vaccination. Fish were placed in 100l seawater tanks and exposed for one hour. Mortality levels were recorded.
In 2010, a randomised, replicated, controlled study in Canada (Burnley et al., 2010) found the vaccine, Lipogen Forte V1, increased salmon, Salmo salar, survival during an outbreak of bacterial kidney disease when compared with an industry standard. Four other vaccines were not successful, relative to the industry standard vaccine. Groups of salmon were given one of four commercially available vaccines: Lipogen Forte V1, Renogen, Bayovac 5.1 Vet and Alpha Ject 4000. Mortality was measured weekly or biweekly for eight months.
In 2011, a replicated, controlled study in Tasmania, Australia (Costa et al., 2011) found increased survival rates in salmon, Salmo salar, vaccinated (using Yersinivac-B) and then exposed to the disease-causing bacteria, Yersinia ruckeri. Vaccinated salmon showed higher rates of survival than the unvaccinated control group. A trypsinated version of the Yersinivac-B vaccine produced higher survival rates than an untrypsinated vaccine (65% and 52% survival respectively). Y. Ruckeri causes yersiniosis. Groups of salmon were given one of two vaccinations; either Yersinivac-B or a trypsinated version of Yersinivac-B. A control group received no vaccination. Six weeks after vaccination, salmon from each treatment were exposed to Y.ruckeri and mortality levels were monitored for 14 days.
In 2011, a randomised, controlled study conducted in Norway (Lauscher et al., 2011) found that vaccinated salmon, Salmo salar, showed increased levels of survival after exposure to infectious salmon anaemia compared to an unvaccinated control group. Survival levels were lower with increasing strength of vaccine. After 45 days, mortality levels in the vaccinated groups were 55.0%, 28.3% and 10.0% respectively, for vaccines at strengths of 4%, 20% and 100%. Three groups were given one of three different strengths of vaccine at 100%, 20% and 4%. Two control groups were given a mock vaccine and saline. Six weeks after vaccination, all groups were infected with the infectious salmon anaemia virus and mortality was recorded daily for 45 days.
- Gudmundsdottir B.K. & Gudmundsdottir S. (1997) Evaluation of cross protection by vaccines against atypical and typical furunculosis in Atlantic salmon, Salmo salar L. Journal of Fish Diseases, 20, 343-350
- Mikalsen A.B., Sindre H., Torgersen J. & Rimstad E. (2005) Protective effects of a DNA vaccine expressing the infectious salmon anemia virus hemagglutinin-esterase in Atlantic salmon. Vaccine, 23, 4895-905
- van Gelderen R., Carson J. & Nowak B. (2009) Experimental vaccination of Atlantic salmon (Salmo salar L.) against marine flexibacteriosis. Aquaculture, 288, 7-13
- Burnley T.A., Stryhn H., Burnley H.J. & Hammell K.L. (2010) Randomized clinical field trial of a bacterial kidney disease vaccine in Atlantic salmon, Salmo salar L. Journal of Fish Diseases, 33, 545-557
- Costa A.A., Leef M.J., Bridle A.R., Carson J. & Nowak B.F. (2011) Effect of vaccination against yersiniosis on the reltive percent survival, bactericidal and lysozyme response of Atlantic salmon, Salmo salar. Aquaculture, 315, 201-206
- Lauscher A., Krossoy B., Frost P., Grove S., Konig M. & Bohlin J. (2011) Immune responses in Atlantic salmon (Salmo salar) following protective vaccination against infectious salmon anemia (ISA) and subsequent ISA virus infection. Vaccine, 29, 6392-401