Marte Steffina Eidshaug is the new fish health biologist at Blue Analytics. She will be working on histology, biomarkers of health, diagnostics in general and providing consultancy services in the field of fish health.
Marte has completed a Master’s degree in fish health at the University of Bergen. The thesis was entitled ‘The use of biomarkers in the health monitoring of farmed fish’. As part of her Master’s thesis, she established, in collaboration with Blue Analytics, a digital PCR-based method for assessing tissue condition in the gills and heart.
Comparison of histology and biomarkers
In the study, she analysed monthly samples of gill and heart tissue from salmon. Sampling was done from sea transfer in April 2024 until March 2025 at two marine sites. The tissue samples were assessed histologically and analysed for gene expression using digital PCR. By comparing histological findings with levels of selected biomarkers, the methods could be correlated with one another. The results show that biomarkers may be a new and useful tool for monitoring the health status of fish populations.
Seasonal variation in gill tissue repair
The study documented the normal condition of gill and heart tissue and revealed a clear seasonal variation. In autumn, a downregulation of genes associated with the formation of new gill tissue was observed, indicating a reduced capacity for repair. This may make the fish more vulnerable to gill damage during this period.
The fish did not develop gill disease during the sampling period. Blue Analytics will continue its work on developing biomarkers that indicate gill health, as well as investigating whether there is a link between gill and heart health.
“Marthe’s work forms the basis for the development of products and services based on biomarkers. Her expertise in histology also helps to strengthen the work in this field.”
Øyvind Vågnes, external supervisor for Marte’s Master’s thesis and Head of Diagnostics at Blue Analytics
Agent-independent monitoring of gill and heart health
Histology provides a very good description of the condition of the tissue, but the method is both time-consuming and costly. The development of an alternative method to histology, independent of monitoring for various pathogens, will help fish farmers adapt their management of the fish to the current health status of the stock. The use of gene expression profiling of various biomarkers has the potential to predict changes in gill health and, in the long term, to supplement or replace traditional histology.
“My master’s thesis at Blue Analytics gave me valuable insights into both diagnostic work carried out by fish farmers and laboratory analyses. I will be taking this knowledge with me as I move on to new projects within the company.”
Marte Steffina Eidshaug, Fish Health Biologist at Blue Analytics