Biofouling of fish-cage netting: the efficacy of a silicone coating and the effect of netting colour

The efficacy of a silicone coating (Veridian 2000) to reduce fouling on salmon-cage netting was examined at a salmon farm in Tasmania, Australia. Significantly less fouling occurred on the white silicone-coated netting (1.9 kg/m(2)) compared to uncoated white (7.8 kg/m(2)) and black (8.5 kg/m(2)) netting after 163 days immersion. On silicone-coated netting the green alga Ulva rigida dominated the fouling mass, with smaller amounts of solitary ascidians. In contrast, solitary ascidians dominated the uncoated black and white netting and accounted for more than 75% of the fouling mass. Netting colour significantly affected the growth and composition of algal fouling, but had no effect on invertebrate fouling. Cleaning experiments demonstrated that fouling organisms were poorly adhered to the silicone coating and that relatively little effort was required for their removal. Silicone coatings may provide an effective non-toxic solution to reduce fouling on sea-cages and to increase the ease of fouling removal. (C) 2000 Elsevier Science B.V. All rights reserved.