I am not sure that restricting gear always reduces efficiency. Creek I fished as a kid, full of Browns, was rather impervious to bait fishing. Lures and flies, yeah that worked. But it has been shown over and over again that certain gears are significantly less destructive. As Salmo said, it's about limiting kill.

At its simplest, with a 5% mortality rate you can kill 100 fish straight away with a kill-only fishery or you can C&R 2,000 to kill that same 100. The question is what is the value of the fishery? We need to talk about that.

I was always hit with the "value" of the marine mixed stock fishery (sport or troll) was so high because so much money was spent to chase the fish in the ocean. Those same fish, in the bay or river, generated much less economic value per fish killed whether in a net or hook and line.