It’s generally better for the planet to eat frozen grub that's come a lot of food miles than fresh which has travelled fewer miles by air, in fact. According to the enviro-scientists:
The choice to buy frozen matters more than organic vs conventional or wild vs farmed.
There were other conclusions from the study which could be seen as flying in the face of conventional eco-wisdom. According to the assembled boffins:
Catching salmon in large nets as they school together has one tenth the impact of catching them in small numbers using baited hooks and lures.
This directly contradicts the advice offered by Greenpeace, for instance, which says “choose line-caught fish wherever possible”.
Deep waters, these.