This sea bass cage operation off the northern coast of Crete, Greece, maintains 24 circular cages producing approximately 2,500 tonnes annually. The warm Mediterranean waters (18-27 degrees C year-round) drive continuous biofouling dominated by calcareous organisms — principally Amphibalanus amphitrite barnacles, Hydroides elegans tubeworms, and encrusting bryozoans — that can fully occlude net meshes within 4 to 6 weeks of cleaning. Prior to the trial, the farm operated a weekly cleaning rotation requiring a dedicated vessel and four-person crew at an annual cost exceeding 280,000 euros.
In a controlled 18-month comparison, the farm deployed copper-coated nylon nets on 8 cages while maintaining standard untreated nets on 16 control cages with the existing cleaning schedule. Copper-treated nets showed 90 percent less fouling biomass at every sampling interval. Water flow measurements confirmed that copper nets maintained 95 percent of their original permeability throughout the trial, compared to just 40 percent for standard nets at the midpoint between cleanings. Fish in copper-net cages achieved an 8 percent higher growth rate, attributed to sustained water exchange and oxygen supply. The farm has since committed to a full fleet conversion, projecting a net saving of 120,000 euros per year after accounting for the higher net purchase cost.
Mediterranean farms facing similar year-round fouling pressure can explore this site on the aquaculture farm map. The solutions comparison tool evaluates copper nets alongside other options for warm-water conditions. Use the biofouling cost calculator to model the economics for your site, and see the organisms database for profiles of the dominant Mediterranean hard foulers.
Outcomes
Compared copper-coated nets with standard nets over 18-month cycle. Fouling biomass 90% lower on copper nets. Water flow through copper nets maintained at 95% vs 40% for standard nets. Fish growth rate 8% higher in copper net cages.