This paper uses an environmentally extended input-output model of the Irish economy to estimate greenhouse gas (GHG) emissions and economic output multipliers in 2010 for two aquatic (aquaculture products and sea fisheries) and five land-based livestock products (beef and veal, sheep meat, pig meat, poultry meat, and dairy products). Moreover, the Global Value Chain (GVC) framework is adopted to qualitatively understand the structure of Irish food sectors and identify segments of the food value chains with the greatest emissions efficiency and economic potential. Aquaculture is found to have the highest output multiplier and a low to medium carbon footprint compared to pastoral livestock products (beef and veal, sheep meat, dairy). The direct and indirect economic benefits of the aquaculture sector along with the relatively low carbon footprint suggest that additional benefits from an expansion of Ireland’s aquaculture sector can be gained. However, aquaculture is energy intensive, and therefore production requires the efficient use of energy and resources and the employment of low carbon technologies that strengthen aquaculture’s sustainability.