Testing of novel net cleaning technologies for finfish aquaculture

Abstract

To avoid the negative impacts caused by biofouling development, aquaculture nets around the world are periodically cleaned using high-pressure washers. Net cleaning is labour-intense and costly, can damage antifouling coatings on the nets, and pose contamination as well as fish health and welfare risks. To support the environmental sustainability of the growing aquaculture sector, novel net cleaning methods are needed. This study examined low-pressure-, cavitation-, and suction-based cleaning technologies as alternatives to conventional high-pressure cleaning. Using field experiments, cleaning efficacy, cleaning waste generation, and the impact of cleaning on coating integrity and net strength were evaluated. Cavitation and high-pressure cleaning achieved considerably higher cleaning efficacy than low-pressure and suction cleaning. However, a single high-pressure treatment caused up to 53% coating degradation, compared to 2% for cavitation. All technologies produced similar cleaning waste and neither reduced net strength significantly. This study identifies cavitation cleaning as promising technology for biofouling control on aquaculture nets.

Keywords:

• Biofouling
• Atlantic salmon
• Salmo salar
• antifouling
• copper
• cavitation

Acknowledgements

The authors thank Måsoval AS and Lerøy Seafood AS for supporting the placement of net samples at their sites for biofouling collection. Furthermore, they are thankful for the assistance of Terje Bremvåg, Magnus Oshaug Pedersen, Alessandra Bellucci and Deni Koseto during the execution of the experiments, as well as to Heidi Moe Føre for input into the manuscript draft. This paper benefitted from the constructive comments of three anonymous reviewers.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was supported by the Research Council of Norway under Grant no. 245480/E40. The study received an in-kind contribution from the following Norwegian industry partners: Brynsløkken AS provided the coated net material used in the experiment, Lerow AS supplied the pressure cleaning equipment and their support during the experiments, PSO AS supplied the cavitation cleaning equipment, and Sperre AS provided input into the design of the suction cleaner. No financial interest or benefit has arisen from the direct applications of this study.