My understanding of the situation is that the U.S. federal government has been doing an excellent job of managing fisheries over the past couple of decades — there was an overfishing crisis in the 80’s, but since then we’ve gotten our act together and implemented population monitoring and fishing quotas. There are definitely problems (especially with certain methods of fishing causing bycatch problems or habitat destruction), but researchers and regulators seem to be mostly on top of them. Farm-raised fish have their own set of challenges — mainly health concerns and the potential for environmental disasters [0] — so there’s not necessarily a clear winner between farmed and wild fish. It also depends heavily on the particular species of fish.

My source for this is an elective class I took at Oregon State University a few years ago, taught by a professor who is deeply involved in fishery research and management. So perhaps he was biased, but from what he presented I was thoroughly impressed with the sustainability practices of the seafood industry. One of my big takeaways was that wild Alaskan halibut in particular (which is what McDonald’s uses) is among the best seafoods, and one of the most sustainable foods in existence.

[0]: https://en.wikipedia.org/wiki/Cypress_Island_Atlantic_salmon...