Abstract
An in-depth analysis of shrimp aquaculture has been conducted using a life cycle approach to gain a better understanding of the sustainability issues facing the industry. The environmental footprint of the complete supply chain of block-frozen shrimp has been evaluated within this study using Life Cycle Assessment (LCA). The analysis is based on shrimp production in Thailand as a case study, in which frozen shrimp represents the principal shrimp aquaculture product. The results from the LCA study show farming is the key life cycle stage generating the most significant environmental impacts, particularly marine toxicity, abiotic depletion and global warming, which arise mainly from the use of energy, shrimp feed and burnt lime. Eutrophication caused by wastewater discharged from the shrimp ponds has also been identified as a significant problem. In addition to the key life cycle stages, this study has identified the key environmental issues and improvements needed in aquaculture management practices. The identified environmental impacts can be reduced by using inputs from sustainable sources, such as domesticated broodstock and local sources of post-larvae, and by replacing burnt lime by limestone. Further improvements could be achieved by using jet aeration equipment rather than paddle-wheel aerators because of their better energy efficiency. Better onfarm management practices should be implemented to improve the quality of ponds, including optimisation of stocking density, feeding rate, water exchange and operation of the aerators. It is also necessary for farms to treat wastewater before its release into natural receiving water to minimise the eutrophication problem. In order to identify more sustainable farming systems, the study has also compared the environmental performance of five different farming types: (i) a Conventional & CoC farm, applying an intensive farming system coupled with an environmental management system (the ‘Code of Conduct for Responsible Marine Aquaculture’, known as ‘CoC’); 11 (ii) a Biological & CoC farm, practising an intensive farming system with implementation of CoC and minimising the use of chemicals; (iii) a Probiotic farm, using probiotic substances to digest waste in shrimp ponds; (iv) an Ecological farm, aiming to raise shrimps naturally by optimising the ecological intensity of inputs; and (v) a ‘Goingto-be-Organic’ farm, undergoing conversion from conventional to organic farming primarily by operating at a lower stock density and completely eliminating chemical inputs. The LCA results show that potential impacts of the various farming types are closely related to the choice of farming site, culture technique and management strategy. The Conventional & CoC farm has the highest impacts because of the higher inputs of energy, feed and burnt lime. The use of probiotics (in Probiotic farm) and biological extracts (in Biological & CoC and Going-to-be Organic farms) in place of chemicals significantly reduces the ecotoxicity impact. The Ecological farm proves to be the least problematic in terms of eutrophication, primarily as a result of reduced feeding rate and improved feed management. If equal importance is attributed to all the impact categories considered in the CML Baseline method, the environmental performance of the different farming systems can be ranked from best to worst as: Going-to-be-Organic, Probiotic, Ecological, Biological & CoC and Conventional & CoC farms. Similar ranking is obtained for the other two life cycle impact assessment methods used here, i.e. EPS 2000 and Ecoindicator 99. This study has also highlighted that economic priorities and social benefits coupled with environmental consideration must be analysed from the life cycle perspective. The results from LC A can be used to formulate a more sustainable policy and management framework for the shrimp aquaculture industry. Participation of the stakeholders along the supply chain is also important for policy formulation and implementation of sustainable management frameworks. Roles and responsibilities of various governmental organisations must be clearly defined, together with the establishment of laws and regulations to support the implementation of policy aligned with environmental objectives. Environmental management should also include sustainable management of aquaculture resources and farming practices with strong support from associated industries to improve the overall environmental performance of shrimp production as a whole. The environmental performance of shrimp production is increasingly becoming a commercial concern due mainly to the consumer demand for environmentally-friendly products. The environmental issues identified in this LCA study are therefore used to analyse various certification schemes that have been introduced or proposed for production of farmed shnmp, and to propose an colabelling initiative for shrimp aquaculture products. The principles of the current certification systems are broad, with insufficiently specific operational guidelines for their practical application. The principles and criteria identified by LCA provide a more comprehensive perspective on the environmental impacts, covering both upstream and downstream activities as well as local and global impacts. Specific criteria recommended for ecolabelling of shrimp aquaculture products, identified by the LCA study are: the amount of energy consumed by the aerators, the proportion of fishmeal in the feed, the quantity of burnt lime used for pond management, and the nutrient loading of wastewater discharged from the shnmp pond. Recommendations for guiding consumers on environmentally-fiiendlier’ products are also made to promote more sustainable shrimp consumption. The wider perspective and more comprehensive coverage of environmental impacts provided by LCA have given a better understanding of environmental consequences of shrimp production. This study of shrimp aquaculture has demonstrated that LCA can be a useful tool to inform and facilitate the move towards a more sustainable productionconsumption system. Further studies using LCA to compare aquaculture-based and capture-based fisheries products, as well as agricultural products, would also be useful to gain better understanding of the environmental footprint of different food production system as a whole.