why are multifilament gillnets okay but mono not.

[JOHN11]

Hi. I read this statement on an old posting on this website, can you please explain why multi is okay but monofilament gill netting is illegal:

" Multi-mono gill nets are OK in Scotland: salt water, mesh size legal for fish you retain, don't keep undersized fish. A bit tricky to use without some sort of boat, however. Monofilament gill nets are absolutely illegal to use in fresh or salt water. "

 

[Robson Valley]

We fished some mono gill net many years ago. Was a pale yellow green and ABSOLUTELY invisible in the water.
Lead line and floats and nothing???? in between. Hate to get tangled in that stuff. Anything stranded, you can see.
Maybe, just maybe, that invisibility means more by-catch such as turtles, mink, diving waterfowl and so on?