The term "commercial fishing" encompasses a multitude of different places, methods, regulatory regimes, monitoring practices, and more, and they range from _extremely_ well managed and sustainable to utterly disastrous.
Bluefin Tuna happens to be one of the worst, because it's one of the very few where the species is so valuable that as it gets rarer, the price just climbs and continues to justify ever smaller catches. This is pretty bad for Bluefin Tuna, and could result in it being the first every commercially fished marine fish species to go extinct (yes; that's correct: no marine fish species has _ever_ gone extinct from human fishing).
I'm an ecologist who got his degree in fisheries ecology. I'm very much in favor of better, more cohesive fisheries management. But I don't believe we will make any progress by tarring entire industries. All you do is create enemies out of allies.