I'm experimenting with circle hooks for both herring in the salt and eggs/shrimp in the tribs. My success has been mixed.

Since I normally fish bobber/eggs in the tribs, the circle hook has not been as effective as I would prefer. My guess is that when fishing a bobber/egg, the hook needs to bury itself in the roof of the mouth. But a circle hook needs soft tissue, such as the tonuge, or a lip/jaw to get a soild hookup. Trying to bury a circle hook in the roof of the mouth is difficult, thus a few too many lost fish. But I like the "no hookset" advantage of a circle hook so I will keep trying.

For herring rigs in the mainstem Columbia, I have not been any more or less successful using circle hooks than standard octopus hooks. I don't normally set the hook when trolling a herring rig anyway so there is no real advantage. Circle hooks seem to be safer since it's much more difficult to hook yourself, or your buddy, than octopus hooks.

When fishing the blue water, I always use barbless hooks, rather than octopus hooks with the barb pinched down. The deep bend in barbless hooks is very close to being a circle hook. I believe it's much more difficult to throw a circle hook, or a barbless hook, when fishing the ocean.

My .02