Size selectivity is the one (almost) legitimate argument. Trouble with that one is that non-target species (piscatorial and otherwise) of similar girth get just as stuck as salmon... Then the wild fish factor.... Besides that, my observation has been that as the fish get smaller, so goes the mesh size.

I am less upset about tribal gillnetting (the terminal tributary variety) these days, because at least they select for target stocks (of course, those also kill too many wild fish).

Had gillnet fisheries been managed better over the past several decades, they would still be sustainable today, in my opinion. We've been taking too much, too non-selectively, for too long, and at this point, there's probably not a net fishery left that doesn't kill endangered fish or endangered something else.

It's time for commercial fisheries to evolve, before there's nothing left to catch. If our habitat's as screwed as we're told it is, we at least need to stop wasting potential spawners... don't we?