The global food production sector is growing and in many areas farming systems are intensifying. Although food production from all sectors has environmental impacts and environmental costs, public opinion and regulatory oversight amongst the sectors in this area is uneven. In order to understand better the place of aquaculture amidst the other food production sectors in regards to environmental costs, the first session of the FAO Committee on Fisheries' Sub-Committee on Aquaculture recommended "undertaking comparative analyses on the environmental cost of aquatic food production in relation to other terrestrial food production sectors". Comparisons can be useful for addressing local development and zoning concerns, global issues of sustainability and trade and consumer preferences for inexpensive food produced in an environmentally sustainable manner. Methods to assess environmental costs should be scientifically based, comparable across different sectors, expandable to different scales, inclusive of externalities, practical to implement and easily understood by managers and policy-makers. These proceedings include review papers describing methods for such comparisons as well as the deliberations of their authors, a group of international experts on environmental economics, energy accounting, material and environmental flows analysis, aquaculture, agriculture and international development.