Aquaculture Insights – A Life Cycle Assessment of the environmental performance of copper mesh

nathanAyerBy Nathan Ayer
Senior Sustainability Advisor, EarthShift Global

 

Nathan Ayer is EarthShift Global’s Senior Sustainability Advisor and has extensive experience in environmental management issues in the aquaculture industry.

A study by EarthShift Global and the International Copper Association (ICA) using Life Cycle Assessment (LCA) to measure the environmental performance of copper alloy mesh was published in the peer-reviewed journal Aquaculture, the premier science journal for the industry. Copper alloy mesh is an alternative to current aquaculture industry standard nylon mesh and was developed by a group of ICA member companies for net-pen aquaculture systems.

The LCA article highlights a range of operating conditions conducive to the use of copper-based mesh and also reveals previously unquantified environmental benefits of using copper mesh throughout the aquaculture supply chain. Nylon mesh used 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 properties of copper alloy mesh and its more rigid structure have the potential to lead to an improved culture environment. Specific benefits of copper alloy mesh include reduced predatory interactions, reduced fish escapes, reduced maintenance and net replacement and less waste due to the recyclability of the copper-mesh materials. Improvements in operating performance, achieved by using copper alloy mesh 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. The salmon farmer collected data on operating inputs and outputs, fish growth, infrastructure inputs, and transport of salmon feed within the supply chain. These data were compared with industry-average net pen operating performance in Chile for 2012. The 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.

Salmon net pen with copper-alloy mesh in Chile, 2012

Salmon net pen with copper-alloy mesh in Chile, 2012

 

The LCA study also reveals a number of indirect environmental benefits that could be achieved through the supply chain but have not been previously quantified. Results of the study suggest that deployment of copper alloy mesh nets can result in a reduction of material and energy inputs both on-site (feed and energy) and across the supply chain (inputs to feed, raw material extraction). This can lead to reduced contributions to a number of negative environmental impacts. For instance, 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%.

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).

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 result of particular interest in the study is that the use of copper alloy mesh could lead to a 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. 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.

Throughout its ongoing partnership with the ICA, EarthShift Global has used its expertise in life cycle management tools to enable the ICA and its member companies to quantify the environmental performance of this innovative aquaculture technology, benchmark the technology relative to industry averages, inform sustainable design of their system and communicate the results of this work to their stakeholders.

Our work with the ICA will continue in the coming months as there are several more pilot studies underway. EarthShift Global will collect additional data to verify the results of the most recent published study.

For further information please contact Nathan Ayer at nathan@earthshiftglobal.com or Robert Dwyer at robert.dwyer@copperalliance.org. To view the abstract of the journal article and find download information, visit: http://dx.doi.org/10.1016/j.aquaculture.2015.11.028


 

EarthShift Global specializes in Life Cycle Assessment (LCA). They are pioneers of Sustainability ROI, helping organizations integrate environmental, social, and economic sustainability into their business and manufacturing operations.