MSc in Aquaculture Marwa Mechlaoui at the Norwegian College of Fishery Science (NFH) will Friday 30 January 2025 hold her trial lecture and defend her thesis for the PhD degree in Natural Science.
Trial lecture on assigned topic will take place at 10.15: "Correlates of vaccine protection in fish - with focus on immune responses of the host and the nature and content of the antigen"
Later, at 12.15 he will defend her thesis entitled: "Immune responses in Atlantic salmon during full-scale commercial production at sea"
Professor and head of department Bjørn-Petter Finstad at NFH will lead the disputation.
Popular Science Summary
The Norwegian aquaculture industry has grown significantly over the past five decades, becoming a global leader in salmon production. However, this expansion has introduced challenges, particularly in managing bacterial and viral diseases, as well as salmon lice, which threaten fish health and farm productivity. Most losses occur during the seawater phase of salmon farming, where fish are exposed to environmental stressors such as temperature fluctuations, salinity changes, oxygen variability, transportation, delousing, and disease outbreaks. This thesis investigates the welfare and immunity of Atlantic salmon throughout a full production cycle at a commercial farm in northern Norway. Fish were sampled from the hatchery before vaccination and every six weeks post-sea transfer until slaughter. Salmon were vaccinated with a multivalent oil-adjuvanted vaccine, and the study focused on vaccine-induced inflammatory responses, antibody production, environmental impacts on immunity, and the effects of mechanical delousing on fish health. Key findings revealed that vaccinated salmon developed long-lasting antibody responses against Aeromonas salmonicida, Vibrio anguillarum, Yersinia ruckeri, and infectious pancreatic necrosis virus (IPNV) for up to 20 months post-vaccination, with higher responses to A. salmonicida and V. anguillarum. Low temperatures and seasonal photoperiod variations did not affect antibody responses. Vaccine-induced granulomas persisted at the injection site for up to 50 weeks, showing evidence of local IgM production, whereas the head kidney likely contributed to the long-term secretion of IgM. Mechanical delousing using the Hydrolicer system negatively impacted fish health, causing reduced growth, increased mortality, external injuries, gill stress, and organ pathology. Cellular changes in the thymus, including increased T cell markers, were observed after repeated treatments, needing further investigation. In conclusion, vaccination induced prolonged immune responses and inflammation, while delousing treatments adversely affected fish health.
Evaluation Committee
Supervisors
Streaming
Both the trial lecture and defense and will be streamed and recorded:
Thesis
The thesis is available in Vitenarkivet