Life Cycle Assessment for environmentally sustainable aquaculture management: a case study of combined aquaculture systems for carp and tilapia

Life Cycle Assessment (LCA) was applied to evaluate the potential environmental impacts associated with two-net cage aquaculture systems of common carp (Cyprinus carpio carpio) and tilapia (Oreochromis niloticus) in the Cirata reservoir, Indonesia. The studied system included fingerling production in hatcheries, fish rearing in cages, and transport of fry and feed as well as that of harvested fish to markets. The environmental impact indicators were calculated based on the annual production in 2006-2007 using the CML2 Baseline 2000 method, and expressed per tonne of fresh fish delivered to the market. The rearing performances and the environmental efficiency of the system were highly dependent on the lake water quality. Therefore the location of the cages and associated practices influenced the environmental impacts. Feed was identified as the major contributor to land occupation, primary production use, acidification, climate change, energy use and water dependence. Those impacts were mainly linked to the production of fishmeal followed by the production of crop-based feed materials and the production of electricity for feed processing. Eutrophication was mainly the consequence of the fish growing stage and linked closely to nutrient loading from cages. Better feeding practices to reduce feed conversion ratio (FCR), as well as improvement of feed composition by using less fishmeal and more local plant-based materials along with improving energy efficiency of feed production processing should be implemented to improve the environmental profiles of carp and tilapia production. The reduction of FCR from 2.1 to 1.7 could decrease eutrophication by about 22%. However, it is of first priority to reduce the number of cages in order to improve the water quality of the reservoir. The comparison of Cirata reservoir fish culture to other sources of animal protein revealed that it generated average energy use but high eutrophication level. LCA was demonstrated to be a useful tool for decision-making when targeting improved environmental sustainability of cage aquaculture. (C) 2013 Elsevier Ltd. All rights reserved