AuntyM, I've commented on the use of seines selectively before...I thought it was this thread but maybe not.

It could happen in a couple of ways, but it's a lot of work. You either have to push the corks down to let selected fish out, or dip 'em out, which can be pretty damaging. Either way you'd have to be able to determine the species and whether it's clipped or not to decide what to do with it.

I've released seals, jellyfish, and birds this way from a seine. No harm, no foul. (no pun intended) That's also how they get dolphins out of the tuna seines, from what I understand....push down the corks and out they go.

Imagine, though, 1000 pinks and 3 native steelhead/chinook in a seine. You'll never see the steelies until they land on deck.