ROV Robotic Net Cleaning

ROV (remotely operated vehicle) net cleaners are submersible robots controlled from a surface vessel that systematically clean cage nets underwater using rotating disc heads, high-pressure water jets, or a combination of both. The operator monitors the cleaning process via onboard cameras and sensors, guiding the ROV across net panels from the surface while fish remain in the pen. These systems can operate at depths of 30 metres or more and in current conditions that would be dangerous or impossible for commercial divers.

ROV cleaning has become the dominant method on large-scale offshore salmon farms in Norway, Scotland, and Tasmania, where cage depths, exposed locations, and strict diver safety regulations make manual in-situ cleaning impractical. The machines handle everything from light biofilm to heavy encrustation by barnacles, mussels, and hydroids. Modern units integrate GPS positioning and net-tracking software for repeatable cleaning patterns, and some models collect fouling debris via onboard suction systems to minimise discharge into the water column — addressing one of the main environmental criticisms of mechanical net cleaning.

The financial barrier is substantial. A single ROV cleaning unit costs EUR 300,000-800,000, and each deployment requires a support vessel, trained pilot, and deck crew. For farms with fewer than 10-12 cages, contracting a specialist cleaning service is usually more economical than owning equipment outright. The cost calculator models both ownership and contract scenarios against farm size and cleaning frequency. Despite the high price, ROV cleaning delivers consistent results that protect net integrity and fish welfare — the methods comparison ranks it among the top-scoring mechanical approaches. For farms exploring whether ROV technology suits their site, the farm map shows CRAB project sites currently using robotic cleaning systems.