Gillnets are very selective, much more so than hook and line. But, their selectivity is by size. Each mesh size selects for a certain size. An example of where it worked well was when Skagit coho needed protection during a chum fishery. Chum mesh (around 6") was mandated and few coho were caught. Then. steelhead seasons started and mesh sizes were dropped. Lots of coho showed up in the catch. The larger mesh protected the coho.

Even though they are size selective they are not hatchery/wild selective.

Further, the selectivity of gill nets has been shown to change size of the spawning population. In BC, the sockeye fishery removed the smaller chum which resulted in an increase in chum spawner size.

There is a time and place for gill nets but they are being overused.