Life-cycle assessment is not necessarily the same as full-cost accounting, and none of these tools is perfect. None of them is able to account for all of the things that we value. For example, life-cycle assessment is very good as an accounting tool to help us understand material and energy demands of the system and how those can contribute to a suite of, let's say, broad-scale environmental impacts like ozone depletion or greenhouse gas emissions. But that being said, if you're asking me which of those three ways of producing salmon has the lowest life-cycle energy demands and associated greenhouse gas emissions, generally speaking, some forms of fishery-based capture, particularly using gears like purse seine, but far less so if you're dealing with trolling.... Trolling burns, relatively speaking, 10 times the amount of fuel that purse seining does. But generally if you want a spectrum, life-cycle energy inputs and greenhouse emissions and associated other impacts are quite low when you have very abundant stocks and you're fishing them using gears like purse seining and net pen aquaculture. From data that currently exist, life-cycle impacts would be the highest for recirculating aquaculture systems per tonne or kilo of salmon that is produced.
I know that others out there would probably disagree with me about placing the recirculating aquaculture at the other extreme, but from the data we've modelled on real systems, that's the case.