Preliminary Results on the Antifouling Potential of Copper Wire and Dyneema® Fiber Combined Twines for Aquaculture Net Cages Abstract: - Antifouling management for aquaculture cage nets has developed over the years to reduce the costs of cleaning the nets and minimize the damages caused to the nets by the encrustation of benthic organisms. There have been various approaches to this end such as using toxic paints (TBT-SPC, etc.) and nanomaterial coatings, mechanical cleaning using brushes, and constructing the net using copper alloys instead of nylon (or other) material, etc. We designed and constructed experimental fish farm nets substituting Dyneema® fibers with uncoated copper wire 0.15-0.2 mm in diameter by 5%, 10%, 20%, and 40% and deployed them in a commercial operating fish farm for almost 7 months. We examined their antifouling performance based on the percentage of mesh openness remaining by the end of the experimental period. The results showed that the antifouling performance increased with copper substitution level and peaked at a level of 29.79% and maximum mesh openness at 46.5%. Key-Words: - antifouling, aquaculture cage nets, copper wire, Dyneema® fibers, marine aquaculture Received: January 9, 2023. Revised: April 29, 2023. Accepted: May 28, 2023. Published: June 19, 2023. 1 Introduction It should be noted that typical nets are usually made from synthetic fibres like nylon, polyester, HDPE, etc. Nylon is mostly preferred due to its breaking load and durability, [1]. However, these nets are more expensive than standard synthetic materials and affected by UV radiation when exposed to the sun, [2]. A major problem in aquaculture is the fouling of the nets from benthic fauna and flora creating many problems to the health of the cultivated organisms and the net material characteristics, [3], [4]. Antifouling management for aquaculture cage nets was developed over the years to reduce the costs of cleaning the nets and minimize the damages caused to the nets by the encrustation of benthic organisms. At the same time, the benefits of the prevention of fouling are numerous including reduction of net drag, increased water circulation within the nets, and improved rearing performance for the cultivated organisms. The main method so far has been the painting of the nets with a paint that includes among others, a toxic metal – mainly copper and zinc - which prevents the establishment of a biofilm which is the basis for the development of bacteria colonies at first, and subsequently other organisms, [5], [6], [7], [8], [9]. These paints are the most preferred method of anti-fouling until today due to their results. However, it has been shown that they are harmful to the marine environment even in small concentrations, [6], [10], [11]. High copper concentrations have been observed in sediments near marine fish farms where antifouling paints are used such as in the cases of salmon, [12], and European seabass and Gilthead seabream farms, [6]. Previous studies in Greece have shown that zinc and copper can be measured in the tissues of European Seabass and Gilthead seabream fish but at levels much lower than those allowed for food for human consumption, [6]. Such findings led to the establishment of guidelines for the use of such paints all over the world and mainly the restriction of their use and reduction or even elimination of WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT DOI: 10.37394/232015.2023.19.59 Alexis Conides, Ilias Kallias, Efthimia Cotou, Panos Georgiou, Ioannis Gialamas, Dimitris Klaoudatos E-ISSN: 2224-3496 607 Volume 19, 2023 ALEXIS CONIDES 1 , ILIAS KALLIAS 1 , EFTHIMIA COTOU 1 , PANOS GEORGIOU 1 IOANNIS GIALAMAS 1 , DIMITRIS KLAOUDATOS 2 1 Hellenic Centre for Marine Research, 46.7 km Athens-Sounion, Anavyssos 19013, GREECE 2 Department of Agriculture, Ichthyology and Aquatic Environment, University of Thessaly, Phytokou Street, 38 446 Volos, GREECE