Could make it easier to assess the quality of salmon eggs

Today, salmon eggs are assessed mainly by their appearance. Sonali Nadeeshani Kaththriarachchi’s doctoral research suggests that characteristics of the eggs and the surrounding fluid could provide earlier and more reliable assessments. She is now preparing to defend her thesis.

Woman with dark hair and white shirt against a concrete wall

Sonali Nadeeshani Kaththriarachchi defends her doctoral thesis 10.11.2026. (Photo: Cryogenetics AS)

Published Oct. 27, 2026 9:13 AM - Last modified Nov. 2, 2026 1:26 PM

Atlantic salmon is one of the world’s most important farmed fish species. Successful salmon farming depends on producing high-quality eggs, but there is currently no reliable way to identify poor-quality eggs before fertilisation.

Traditional assessments are based mainly on visible characteristics, which do not necessarily reflect the eggs’ biological condition. Sonali Nadeeshani Kaththriarachchi has investigated whether this can be improved.

– The aim of this PhD project was to identify measurable characteristics of salmon eggs and ovarian fluid that could help predict fertilisation and early development, she explains.

Eggs and ovarian fluid from 16 female fish were examined using a range of methods, from microscopy and simple physical and biochemical measurements to more advanced analyses of proteins and lipids. Fertilisation and subsequent development were monitored to investigate whether the characteristics measured in the eggs were associated with later reproductive success.

– The study identified the distribution of lipid droplets in the eggs as a potential indicator of egg quality. Characteristics of the ovarian fluid, as well as specific proteins and lipids, were also associated with reproductive outcomes, says Sonali.

The findings provide greater insight into egg quality and a basis for developing practical assessment tools. According to Kaththriarachchi, such tools could help reduce losses and make salmon farming more efficient and sustainable.

Sonali Nadeeshani Kaththriarachchi was part of the PhD programme in Applied Ecology and Biotechnology. The title of her thesis is “Oocyte Quality Parameters Predictive of Fertilising Potential in Atlantic Salmon (Salmo salar L.).”.

The main findings of the doctoral thesis:

  1. Lipid droplet distribution in Atlantic salmon eggs was identified as a promising, simple indicator of egg quality and reproductive success. 
  2. Ovarian fluid pH and AST activity showed associations with reproductive outcomes. 
  3. Proteomic analysis identified several ovarian fluid proteins associated with reproductive outcomes. 
  4. Lipidomic analysis revealed association between egg lipid composition with hatching success.
Tags: public defence