Working with Japanese food, I have seen my fair share of wild and farmed salmon. Unfortunately, wild salmon has never really been a viable option due to its price tag, scarcity, short season, and the fact that salmon is the most popular option for sushi.
I am a big advocate for responsibly farmed salmon for many reasons; beyond supply and demand, I believe many parts of the salmon industry have evolved dramatically over the last three decades, responding well to concerns and always improving. Try and seek out fisheries with high standards for husbandry, low-environmental-impact farming, sourcing sustainable feed, and with a low density and fallow system working in harmony with the local wild animal population.