Atlantic salmon is one of the most important, farmed fish species worldwide. Successful salmon farming depends on the production of high-quality
eggs, but there is currently no reliable way to identify poor-quality eggs before fertilisation.
Traditional assessments are mainly based on visual characteristics and may not fully reflect the biological condition of the eggs. Sonali Nadeeshani Kaththriarachchi set to investigate whether this could be changed.
"This PhD project aimed to identify measurable characteristics of Atlantic salmon eggs and ovarian fluid that could help predict fertilisation and early developmental success", she says.
Eggs and ovarian fluid from 16 females were examined using several approaches, ranging from microscopy and simple physical and biochemical measurements to more advanced analyses of proteins and lipids. Fertilisation and subsequent development were followed to determine whether characteristics measured in the eggs were related to later reproductive success.
"The study identified the distribution of lipid droplets within the eggs as a promising indicator of egg quality. Properties of the ovarian fluid, as well as
specific proteins and lipids, were also associated with reproductive outcomes", says Sonali.
These findings increase our understanding of egg quality and provide a foundation for developing practical assessment tools that could reduce losses and contribute to more efficient and sustainable salmon farming.
Sonali Nadeeshani Kaththriarachchi have been associtated with the PhD prgramme Applied Ecology and Biotechnology and her thesis is titled "Oocytes quality parameters predictive for fertilising potential in Atlantic salmon (Salmo salar L.)".
The main findings of the PhD thesis:
- Lipid droplet distribution in Atlantic salmon eggs was identified as a promising, simple indicator of egg quality and reproductive success.
- Ovarian fluid pH and AST activity showed associations with reproductive outcomes.
- Proteomic analysis identified several ovarian fluid proteins associated with reproductive outcomes.
- Lipidomic analysis revealed association between egg lipid composition with hatching success.