UV light treatment uses ultraviolet-C (UVC) radiation — typically at 254 nm wavelength — to kill or inhibit fouling organisms on submerged surfaces. At sufficient dosage, UVC disrupts DNA in bacterial biofilms, microalgae, and invertebrate larvae, preventing the initial colonisation stages that lead to heavy macrofouling. Systems range from UV lamp arrays mounted inside seawater intake pipes to experimental LED panels integrated directly into net cage structures.
The technology works best as a preventive measure on accessible, relatively flat surfaces. Hatcheries and land-based recirculating aquaculture systems already use inline UV sterilisers to control waterborne pathogens and fouling in pipework, and that application is well proven. Extending UV treatment to open-water cage nets is more challenging — water turbidity attenuates UV penetration rapidly, and complex three-dimensional net surfaces create shaded zones that larvae exploit. Energy consumption is also significant: maintaining effective UV dosage across a full-size salmon cage would require substantial power infrastructure that most offshore sites lack.
Where UV treatment fits well is as an early-stage complement to other methods. Running UV panels during the spring larval settlement window can reduce the initial fouling load that later methods must address, lowering overall cleaning frequency and cost. The methods comparison shows how UV pairs with mechanical cleaning and foul-release coatings in integrated programmes. Check the cost calculator to model energy costs against fouling reduction benefits, and browse the glossary for technical terms related to UV dosimetry and biofilm formation stages.
Pros
Zero chemical discharge Effective against biofilm and early-stage larvae Can be integrated into water intake systems
Cons
Limited penetration — works best on flat, accessible surfaces High energy consumption for large-scale deployment Less effective once macrofouling has established