New research indicates that salmon gills and olfactory organs respond to H2S exposure by activating genes associated with stress response and immune system activation.
A recent study by Nofima, the Norwegian food research institute, in collaboration with international researchers, has uncovered significant insights into how Atlantic salmon react to prolonged exposure to low levels of hydrogen sulphide (H2S) in recirculating aquaculture systems (RAS).
The findings, published in Ecotoxicology and Environmental Safety, are expected to have important implications for fish health and welfare in land-based salmon farming.
Hydrogen sulphide, a toxic gas that can form in RAS, particularly at higher salinity levels, has been linked to health issues and mortality in salmon. The study examined how salmon are affected by sustained exposure to low, non-lethal concentrations of H2S, a condition that can occur during normal production in RAS facilities.
Key findings from the research indicate that the salmon’s gills and olfactory organs respond to H2S exposure by activating genes associated with stress response and immune system activation.
The study also discovered that salmon mucosal surfaces, such as skin, gills, and nose, have a natural ability to detoxify hydrogen sulphide. Additionally, the researchers identified protein markers in the mucus from the skin and gills that could be used for non-invasive testing of H2S response in fish.
“Our findings suggest that salmon can largely adapt to the low H2S levels we tested, without serious negative health effects,” said Carlo C. Lazado, project leader at Nofima. He emphasized the importance of careful monitoring and control of H2S levels in RAS facilities to ensure fish welfare.
The study’s results could lead to improved risk assessment and the establishment of limit values for H2S in RAS, contributing to more sustainable and efficient land-based salmon farming. These findings are particularly relevant for facilities where H2S levels may be higher than in open sea environments.
Carlo Lazado will present further details of this research at the “Smolt Production in the Future” conference on 16-17 October 2024.
