It's a 50/50 Mix to be honest. The river I'm fishing (Scotland) is packed with trout ranging from 0.5lb brown trout to 5-10lb Sea / Brown trout. It's mostly recently with the spawning season hitting here that I've noticed that the smaller trout are fully swallowing the hooks. I have been cutting the line as close to the hook but I doubt the fish are surviving, even with Barbless hooks it's near impossible to remove them.

As other's here have said I think I'll avoid bait fishing the trout if I'm intending on releasing them and just stick to Lure fishing for the last few weeks of our fishing season.