Comparative Growth and Survival of Juvenile Atlantic Cod (Gadus morhua)Cultured in Copper and Nylon Net Pens

Abstract

Bio-fouling on net pens has been a major concern for the marine aquaculture industry. As cage systems increase in size, so does the surface area for the attachment of colonial organisms that create drag on the net, reduce water flow important to fish health, and increase operational expenses due to net cleaning. To solve this problem, the International Copper Association (ICA) has been developing copper alloy netting for sea cages. Copper netting has unique properties that minimize bio-fouling, reduce the risk of fish escapement, prevent predators from entering the net pen, and is recyclable. To test the alloy netting, an experiment was conducted to compare juvenile cod cultured in traditional nylon nets with cod grown in Seawire copper netting (Seawire@Luvata.com). Six, 0.78 m 3 cages were each stocked with 200 Atlantic cod (Gadus morhua) averaging 29 ± 2.2 g and grown for 4 months in coastal waters of New Hampshire, USA. Results of the study indicated no significant differences in cod growth, survival, feed conversion ratio (FCR), specific growth rate (SGR), or Fulton's condition factor (K) between the fish grown in the copper alloy and nylon nets. A chemical analysis was conducted on the cod and indicated no differences in copper levels in muscle, liver and gill tissues taken from the net treatments. Nylon nets with antifouling paint accumulated significantly more bio-fouling than the copper nets. Materials that were in direct contact with the copper netting (plastic cable ties) fouled heavily with hydroids indicating minimal leaching to the environment. This study describes some of the beneficial attributes of copper netting, however future studies need to be conducted over a longer period of time, on a larger scale, and in a more energetic environment to definitively test the utility of this new product.

Construction, Assembly and System Deployment of a Fish Cage With Copper Alloy Mesh Pen: Challenging Work Load and Estimation of Man-Power

“…The higher mechanical strength of the copper alloy fish net pens prevents the loss of fish through escapes (Dwyer and Stillman, 2009;Drach, 2013). Also Chambers et al (2012) reported that the strength of copper netting also deters predators such as seals and sharks.…”

“…Besides the mechanical, economic or environmental advantages of copper alloy mesh compared to the traditional nylon nettings (Chambers et al, 2012;Aufrecht et al, 2013;Drach, 2013;González et al, 2013;Ayer et al, 2016;Efstathiou et al, 2016;Kalantzi et al, 2016;Yigit et al, 2016;Buyukates et al, 2017;Yigit et al, 2017Yigit et al, , 2018, and the higher structural stability of the copper alloy nets exposed to high energy water conditions assuring volumetric integrity in the cage environment and preventing deformation on the structure (Berillis et al, 2017), the construction and assembly of the new technology mesh pens and moreover forming the material into a fish cage is a new challange still remaining as a question to be answered and an issue that might interest fish cage producers and net manufacturers. Moving cage aquaculture to more exposed sites has brought cage farmers to re-consider materials and equipment for cost effective production with higher economic benefits and production of healthier fish.…”

The Use of Copper Alloy in Aquaculture Fish Net Pens: Mechanical, Economic and Environmental Advantages

“…The fish net pens made of copper alloy appear to have comparative mechanical, economic and environmental advantages over the conventional polymer ones (Chambers et al, 2012;Aufrecht et al, 2013;Drach, 2013;González et al, 2013;Ayer et al, 2016;Efstathiou et al, 2016;Kalantzi et al, 2016;Yigit et al, 2016;Buyukates et al, 2017). Copper alloy fish nets have higher structural stability.…”

“…When copper alloy fish nets are introduced into seawater they develop an adherent protective patina layer. That layer inhibits corrosion and resists the attachment of fouling organisms (Chambers et al, 2012;Aufrecht et al, 2013;Drach, 2013). A clean net maintains water movement through the cage for optimal fish health.…”

“…The higher mechanical strength of the copper alloy fish net pens prevents the loss of fish through escapes (Dwyer and Stillman, 2009;Drach, 2013). The strength of copper netting also deters predators such as seals and sharks (Chambers et al, 2012). Lastly, at the end of the copper netting shelf life, it can be sold back to the manufacturer and recycled into another copper net or product.…”