Fat recycling mechanism could boost salmon health

Atlantic salmon possess a biological mechanism for breaking down excess fat, offering potential for improving fish health and sustainability in the aquaculture industry, research shows.

A cellular recycling process, previously found in humans and mice, is also present in Atlantic salmon, scientists at the Roslin Institute have discovered. 

This process, known as autophagy, helps manage and break down excessive fat stored inside cells, which can otherwise lead to an unhealthy fat buildup and impaired immune function.

This discovery lays groundwork for improving welfare and reducing losses in a rapidly growing salmon industry, projected to be worth US$26 billion by 2030.

Dietary change

The discovery could help address a challenge brought about by changes in composition of commercial salmon feed over the past two decades. As the industry expands, traditional fish oils in feed have been replaced with plant-based oils.

These dietary changes may contribute to increased fat accumulation and declining immune health in farmed salmon, leading to higher mortality rates and economic losses, the research team explains.

Cell model

Researchers used salmon cells grown in the lab to study the impact of fat overload, allowing them to study how excess fat affects cell health. 

The team used a compound known to trigger autophagy, called rapamycin, to switch on the cells’ recycling system. This helped the cells store healthier types of fat while reducing levels of proteins linked to unhealthy fat build-up and disease.

The study also identified biological molecules that act as early warning signs of fat overload in cells - these markers could help scientists and fish farmers assess how different feeds impact cellular health.

By understanding how this fat recycling process works at the cellular level, researchers hope to inform future feed formulations that promote better health and disease resilience in farmed salmon.

This research was published in Biochimica et Biophysica Acta – Molecular and Cell Biology of Lipids. The study was carried out in collaboration with colleagues from the Universities of Glasgow and Stirling, and Benchmark Genetics. 

The work was supported by the UKRI’s Food Innovation programme, Scottish Universities Life Sciences Alliance (SULSA), the Biotechnology and Biological Sciences Research Council (BBSRC) and the UK Government’s Seafood Innovation Fund.