I personally don’t eat salmon, wild or domestic, but if you choose to eat fish, wild-caught salmon from sustainable U.S. fisheries is a better choice than many as far as both cruelty and environmental issues go. This question has some good discussions and links for the ecological issues. There is little bycatch involved with wild salmon, so the main potential cruelty involved is to the fish themselves. Much like in any other wild-caught fish industry, they do die by suffocation once pulled from the water. Another potential cruelty issue is that laws have recently been changed to allow sea lions who hang out at dams and eat migrating salmon to be killed.