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Valuable Insights for Aquaculture Sustainability

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New Publication: Study Yields Valuable Insights for Aquaculture Sustainability

Sustainable aquaculture is about more than just what goes on in the water. That’s one insight from a study by EarthShift Global and the International Copper Association (ICA) that has just been accepted for publication by the journal Aquaculture. The article stems from an ongoing collaboration between EarthShift Global and the ICA, where we are applying life cycle assessment (LCA) to quantify the environmental performance of copper-alloy mesh, an innovation from a group of ICA’s member companies designed for application in marine net-pen aquaculture systems.

Copper-based Alternative

The copper-based mesh is an alternative to current industry standard nylon mesh, and is aimed at improving a range of operating conditions at marine fish farms. And while our study found promising results in this area, it also revealed previously unquantified environmental benefits that can be achieved throughout the aquaculture supply chain – a great example of how LCA can provide better decision-making perspectives.  

Nylon mesh in net-pen aquaculture systems is prone to fouling by marine organisms, requires regular cleaning and has a relatively short service life. In contrast, the inherent properties of copper-alloy mesh and its more rigid structure have the potential to lead to: an improved culture environment; reduced predator interactions; reduced escapes; reduced maintenance and net replacement; and less waste going to final disposal due to the recyclability of the netting materials. These improvements in operating performance can result in improved water circulation and dissolved oxygen levels, reduced crowding and stress on fish, improved fish health, and reduced feed inputs. 

Grow-out trials featuring the culture of Atlantic salmon (Salmo salar) in copper-alloy net-pen systems were conducted in Chile between 2010 and 2012 (Figure 1). The salmon farmers collected data on operating inputs and outputs, fish growth, infrastructure inputs, and transport of salmon feed within the supply chain. We compared these data with industry-average net-pen operating performance in Chile for 2012. This trial showed a few operating performance improvements with the copper-alloy nets, including a 10% reduction in feed use, 15% reduction in on-site energy use, 79% reduction in labor hours, and 31% reduction in antibiotic application.

 
Figure 1. Salmon net-pen with copper-alloy mesh in Chile, 2012 (ICA)

While these performance improvements are certainly of interest to fish farmers and industry regulators in terms of improving on-site management of aquaculture operations and reducing costs (Gonzalez et al. 2013), the LCA study also revealed a number of indirect environmental benefits that could be achieved throughout the supply chain that have not been quantified previously. Results of our study suggest that by improving operating performance and fish health, the deployment of copper-alloy mesh nets can result in a reduction of material and energy inputs, both on-site (feed, energy) and across the supply chain (inputs to feed, raw material extraction), which in turn can lead to reduced contributions to a number of environmental impacts. The copper-alloy system has the potential to reduce life cycle greenhouse gas emissions by 16%. Contributions to acidification could be reduced by 17%, and total energy demand across the life cycle modeled in the study was reduced by 18% (Figure 2). 

Figure 2. Comparison of the life cycle impacts of copper-alloy and nylon net-pen systems for the production of 1 ton of live-weight Atlantic salmon (characterized mid-point results using ReCiPe v. 1.07 method and Cumulative Energy Demand v. 1.08).

One of the results we found of particular interest was that the use of copper-alloy mesh could result in more sustainable use of copper in the net-pen aquaculture industry. Copper-alloy mesh is 100% recyclable at end of life and does not require the use of antifouling coatings. This helps to promote a closed-loop cycle in which the copper nets can be continually recycled, putting less pressure on non-renewable copper reserves. This is in contrast to conventional marine aquaculture, in which the use of copper in antifouling coatings represents a linear one-time use of virgin copper and permanent loss of this copper to the marine environment as antifouling coatings degrade.

 

Through its ongoing partnership with ICA, we have used our expertise in life cycle management tools to enable the ICA and its member companies to quantify the environmental performance of their novel aquaculture technology, benchmark their technology relative to industry averages, inform sustainable design of their system, and communicate the results of this work to their stakeholders. This valuable work will continue in the coming months as ICA has several more pilot studies underway and will be working with EarthShift Global to collect further data to verify the results of the most recently published study.

For further information please contact Nathan Ayer at [email protected]. To view the report abstract and find download information, visit: http://dx.doi.org/10.1016/j.aquaculture.2015.11.028

 

About the Author:   Nathan Ayer, EarthShift Global's Senior Sustainability Advisor

Nathan is a big-picture thinker and offers a unique perspective on sustainability based on his interdisciplinary background and range of professional experience in environmental management. Nathan is also a Ph.D. candidate at Dalhousie University, a sessional instructor, and respected researcher. He is a certified LCA practitioner under the ACLCA and leads EarthShift Global's consulting services by conducting LCAs, chairing ISO critical reviews, developing and delivering Life Cycle Assessment training courses, and contributing to software development.