One of my pet environmental peeves. We live here in the great Pacific Northwest, we have access to wonderful wild salmon stock for our tables. Wild salmon is an incredibly good food for you nutritionally, high in omega-3 acids.
Sadly tho we are seeing the widescale introduction of atlantic salmon farming here in the northwest. There is little good about this in my mind. Farmed atlantic salmon are not as nutrionally good for you due to the feedstock they consume; they are dyed pink so that they look attractive; they escape from their pens and compete with the local wild stock; they attract sea lions and seals which are then killed by farmers to protect their fish stock.
Farm raised salmon is cheaper for restaurants than wild salmon, so we are slowly seeing it creep into menus, even here in the Pacific Northwest. The restaurants are not particularly upfront about it — you have to ask very precise questions to make sure you are consuming wild troll-caught Pacific salmon, and not farmed Atlantic salmon.