Before really jumping on the bandwagon, I have actively worked (as in hands in the fish) in what was supposed to be selective beach seine and purse seine fisheries. In both we hade real problems in handling the fish to release. Based on that huge sample of two times, one would need to carefully site the areas where these would be used and the abundance of fish worked on.
"Too many" fish will significantly gum up the works and kill fish intended for release.