Analysis of a novel autonomous underwater robot for biofouling prevention and inspection in fish farms

Biofouling is a challenge for finfish farming as it can impact cage stability and fish health. Amongst others, current strategies against biofouling rely heavily on removal of biofouling using in-situ pressure cleaning of nets. The cleaning waste is released into the water where it can impact the health of the cultured fish. Grooming, the regular cleaning of nets to prevent biofouling communities from establishing, is one novel strategy that is currently explored using tethered underwater robots. In addition, remotely operated vehicles (ROVs) are used for inspection of the net to ensure its integrity and prevent fish escapes, while stationary sensors at the farm barge are employed to extrapolate on environmental conditions in the net pens. In this paper, the requirements for a permanently resident, autonomous and tetherless subsea robot for cleaning and inspection are proposed. As such, the robot aims to combine several application areas and offer a solution to the biofouling challenge while at the same time improving safeguarding of net integrity and monitoring of environmental conditions directly in the pen. Using the SEATONOMY method from an operational viewpoint, the robot's individual operations are analysed. This included i) Environmental condition monitoring, ii) Net and biofouling inspection, iii) Growth prevention and iv) Docking. As a result, the specifications and requirements for the development of a novel robotic system that is able to simultaneously and autonomously perform inspection, growth prevention and monitoring in fish cages were derived. The paper proposes the development of a new technology and biofouling management strategy that will contribute to increase the efficiency and production demands in the aquaculture industry.