Stewart Johnson

Research Scientist

Research in Diseases of Aquatic Animals

Current research and/or projects

I conduct research on diseases, immunology, physiology and husbandry of aquatic animals. My research activities use a multidisciplinary approach and include collaborations with both national and international researchers from a variety of universities, government institutes and industry partners. Disease research focuses on determining the nature of the relationship between fish and three different pathogens: nodavirus (Atlantic cod, turbot), Aeromonas salmonicida (Atlantic salmon) and the sea louse Lepeophtheirus salmonis (Atlantic and Pacific salmon). I apply molecular biology, proteomics, virology, microbiology and immunology to investigate virulence mechanisms of pathogens, the establishment of carrier states, host immunosuppression and disease management techniques such as vaccination.

Ongoing research activities include:

  1. Studies on host-pathogen interactions (L. salmonis and A. salmonicida).
  2. Studies on non-salmonid early larval rearing and development, including ontogeny of the digestive and immune systems and early larval nutrition.
  3. Studies on how husbandry and environmental conditions affect physiology, growth performance and disease resistance of Atlantic cod and Atlantic salmon.
  4. Development of diagnostic methods.
  5. Development of genomics resources for Atlantic cod (see
  6. Development of genomics resources for bivalves.

Research and/or project statements

Professional activities / interests

Professor at:

  • Vancouver Island University
  • Memorial University
  • Dalhousie University

Education and awards

B.Sc., Biology, University of Victoria, 1978

M.Sc., Biology, Dalhousie Universtiy, 1986

PhD., Biology, Simon Fraser University, 1991

NSERC PDF, Zoology, University of British Columbia, 1993

PDF, Hopkins Marine Station, Stanford University, 1996

International experience and/or work

I collaborate with research groups in the Australia, Brazil, Japan, Norway, United Kingdom, and United States in the areas of aquatic animal health, genomics and aquaculture.

I supervise international graduate students and PDFs and have served as external examiner for a number of universities outside of Canada.

I have served on a number of international committees with mandates in aquatic animal health and aquaculture.

Key publications

  1. Feng, C., Johnson, S.C., Hori, T.S., Rise, M., Hall, J.R., Gamperl, K.A., Hubert, S., Kimball, J., Bowman, S. and M.L. Rise 2009. Identification and analysis of differentially expressed genes in immune tissues of juvenile Atlantic cod (Gadus morhua) stimulated with formalin-killed Aeromonas salmonicida. Physiological Genomics 37: 149-163.
  2. Park, K.C., Osborne, J.A., Montes, A., Dios, S., Nerland, A.H., Novoa, B., Figueras, A., Brown, L.L. and S.C. Johnson 2009. Immunological responses of turbot (Psetta maxima) to nodavirus infection or poly I:C stimulation, using expressed sequence tags (ESTs) analysis and cDNA microarrays. Fish Shellfish Immunol. 1: 91-108
  3. Reith, M., Singh, R.K., Curtis, B., Boyd, J.M., Bouevitch, A., Kimball, J,. Munholland, J., Murphy, C., Sarty, D., Williams, J., Nash, J.H.E., Johnson, S.C. and L.L. Brown 2008. The genome of Aeromonas salmonicida subsp. salmonicida A449: insights into the evolution of a fish pathogen. BMC Genomics 9: 427
  4. Liu, X. Afonso, L.O.B., Altman, E., Johnson S.C., Brown, L.L. and J. Li 2008. O-acetylation of sialic acids in N-glycans of Atlantic salmon (Salmon salar) serum is altered by handling stress. Proteomics 8: 2849-2857
  5. Boyd, J.M., Dacanay, A., Knickle, L.C., Touhami, A., Brown, L.L., Jericho, M.H., Johnson, S.C. and M. Reith 2008 Contribution of Type IV Pili to the Virulence of Aeromonas salmonicida subsp. salmonicida in Atlantic salmon (Salmo salar L.). Infect. Immun. 76: 1445-1455
  6. Pérez-Casanova, J. C., Rise M.L., Dixon, B., Afonso, L.O.B., Hall, J.R., Johnson, S.C., and A.K. Gamperl. 2008. The immune and stress responses of Atlantic cod to long-term increases in water temperature. Fish Shellfish Immunol. 24: 600-609.
  7. Hori, T.S.F., Iwama, G.K., Johnson, S.C., Moraes, G. and L.O.B. Afonso 2008. Impairment of the stress response in juvenile matrinxã (Brycon cephalus) exposed to phenol. Comp. Biochem. Physiol. 147: 416-423.
  8. Wagner, G.N., Fast, M.D. and S. C. Johnson 2008. Physiology and immunology of Lepeophtheirus salmonis infections on salmonids. Trends Parasitol. 24: 176-183.
  9. Rise, M.L., Hall, J., Rise, M., Hori, T., Gamperl, A. K., Kimball, J., Hubert, S., Bowman, S. and S.C. Johnson 2008. Functional genomic analysis of Atlantic cod (Gadus morhua) spleen response to the viral mimic polyriboinosinic polyribocytidylic acid (pIC). Dev. Comp. Immunol. 32: 916-931.
  10. Fast, M.D., Hosoya, S., Johnson, S.C. and L.O.B. Afonso 2008. Neuroendocrine response and immune-related gene expression of Atlantic salmon (Salmo salar) subjected to short- and long-term stress. Fish Shellfish Immunol. 24: 194-204.
  11. Garcia, A.S., Parrish, C.C. Brown, J.A., S.C. Johnson and S. Leadbeater 2008. Use of differently enriched rotifers, Brachionus plicatilis, during larviculture of haddock, Melanogrammus aeglefinus: Effects on early growth, survival and body lipid composition. Aquacult. Nut. 14: 431-444.
  12. Afonso, L.O.B., Hosoya, S., Osborne, J., Gamperl, A.K. and S. Johnson 2008. Lack of glucose and hsp70 responses in haddock Melanogrammus aeglefinus (L.) subjected to handling and heat shock. J. Fish Biol. 72: 157-167.
  13. Jones, S.R.M., Fast, M.D. and S.C. Johnson 2008. Influence of reduced feed ration on Lepeophtheirus salmonis infestation and inflammatory gene expression in juvenile pink salmon. J. Aquat. Animal Health 20: 103-109.
  14. Pérez-Casanova, J.C., Afonso, L.O.B., Johnson, S.C., Currie, S. and A.K. Gamperl. 2008. The stress and metabolic responses of Atlantic cod (Gadus morhua, L.) to acute thermal stress. J. Fish Biol. 72: 899-916.