I don't know about the future, but it used to be that sardines were a fish that was not over fished because they weren't that popular. Of course that could change.

Anecdote, not data: I picked up the habit of eating sardines from my Dad who is 97 years young. It's not that he doesn't eat bad stuff, its just that in my lifetime I see evidence that many of the things he ate were healthier than we thought.