In 2009, SINTEF Fiskeri og havbruk, the Norwegian University of Science and Technology (NTNU) and Institutet för Livsmedel och Bioteknik (now SP Food and Bioscience) analyzed the carbon footprint of 22 Norwegian seafood products. A carbon footprint includes both direct and indirect greenhouse gas emissions associated with the production. The products were investigated all the way to the wholesaler.
According to the analysis, 1 kilogram of farmed salmon fillet that is eaten in Paris gives a CO2 equivalent (a unit used to compare CO2 emissions) of around 2.5. The carbon footprint for salmon farming is thus far lower than for cattle production, which emit 30 CO2 equivalents per kilogram. 1 kilogram of pork has a CO2 equivalent of around 5.9. Most of the CO2 emissions associated to salmon farming is related to the production of fish feed.
Useful links (in Norwegian only):
SINTEF Fiskeri og havbruks's report (2009): Carbon footprint and energy consumption of Norwegian seafood products http://www.fhf.no/prosjektdetaljer/?projectNumber=900097
The future in our hands – fact sheet on greenhouse gas emissions (2013):http://www.framtiden.no/201107032164/faktaark/klima/klimagassutslipp-fra-forbruk.html
The Ministry of Fisheries and Aquaculture (FHF) research fund (2008): Pre-project environmental audit: http://www.fhf.no/prosjektdetaljer/?projectNumber=261094