Infectious Diseases in Aquaculture and Salmon Health

Infectious diseases represent one of the most formidable challenges to the sustainability and productivity of global salmon aquaculture. Intensive rearing conditions, high stocking densities and environmental changes have facilitated the emergence and transmission of viral, bacterial and parasitic agents among farmed populations and between farmed and wild stocks. Among these, piscine orthoreovirus (PRV) has attracted significant attention for its association with heart and skeletal muscle inflammation (HSMI), a condition that undermines cardiac function and growth performance in Atlantic salmon. Other maladies, such as cardiomyopathy syndrome (CMS) and erythrocytic inclusion body syndrome (EIBS), further exemplify the diverse array of viral cardiopathies that jeopardise farm yields and fish welfare. Beyond viral aetiologies, bacterial pathogens such as Vibrio spp. and parasitic copepods can exacerbate tissue damage, compromise osmoregulation and predispose hosts to secondary infections. Understanding the multifactorial interactions among host immune responses, pathogen evolution and aquaculture practices is therefore critical for devising targeted mitigation strategies. Recent advances in omics technologies, spatial epidemiology and field-based intervention trials have begun to reveal mechanistic underpinnings of disease resistance, pathogen dispersal and the role of diet and environment in modulating outbreak dynamics. Integrating these insights into management frameworks offers the prospect of reducing mortality, limiting spill-over into wild populations and safeguarding both economic viability and ecosystem integrity.

Research from Nature Portfolio

Recent studies have mapped the coastal distributions of multiple infectious agents in Pacific salmon during their early marine residence. By deploying high-throughput qPCR across thousands of fish along the British Columbia coast, researchers identified seasonal and geographic clusters of pathogen prevalence. These infection hotspots, notably within the Salish Sea migration corridor, correlate with periods of elevated juvenile mortality and suggest locations where targeted surveillance and remediation could yield greatest benefit. The work also highlighted lesser-known viral and bacterial taxa, expanding the catalogue of potential threats to wild and farmed populations and offering new directions for ecological monitoring and risk assessment.

Infectious Diseases in Aquaculture and Salmon Health publication trend

The graph below shows the total number of articles in infectious diseases in aquaculture and salmon health across all publications each year (not limited to Nature Index journals).

Technical terms

Piscine orthoreovirus (PRV): A segmented double-stranded RNA virus implicated in heart and skeletal muscle inflammation in salmon.

Heart and skeletal muscle inflammation (HSMI): A viral disease of farmed salmon characterised by myocarditis and muscle tissue degeneration.

Cardiomyopathy syndrome (CMS): A severe viral cardiopathy in Atlantic salmon leading to high mortality during seawater production.

Quantitative polymerase chain reaction (qPCR): A molecular technique for detecting and quantifying specific nucleic acid sequences.

Erythrocyte: A nucleated red blood cell in fish that contributes to both oxygen transport and innate immune responses.

References

1. Transcriptomics of early responses to purified Piscine orthoreovirus-1 in Atlantic salmon (Salmo salar L.) red blood cells compared to non-susceptible cell lines. Frontiers in Immunology (2024).
2. An Atypical Course of Cardiomyopathy Syndrome (CMS) in Farmed Atlantic Salmon (Salmo salar) Fed a Clinical Nutrition Diet. Microorganisms (2023).
3. The spatial distribution of infectious agents in wild Pacific salmon along the British Columbia coast. Scientific Reports (2023).
4. Analyses and Insights into Genetic Reassortment and Natural Selection as Key Drivers of Piscine orthoreovirus Evolution. Viruses (2024).