Treble hooks are an immoral choice where some fish must be released.
I use 16/0 circle hooks.
First time I think I've disagreed with anything you've had to post Eric.. Ling and Halibut are extremely tough mouthed fish. We are not talking about Salmon fishing with this type of gear run off a spreader bar. I release a lot of ling and the trebles do not cause me problems for the release. Lings mouths are so though the problem is getting hook penetration, not getting the hooks out. I do not anchor, I drift, and I do not feed the fish line or allow time for the lure and bait to be swallowed deeply. As I said I mostly use a 10in hoochy & bait combo, which is quite a mouthful to swallow deeply. I can never recall this rig being swallowed deeply enough to get the front treble caught in a lings gills. I can almost always release the fish with little effort in the water with no harm to the fish. If the fish were injured I could always keep it if I thought it was injured. I can't recall the last time I've ever had had to do that. Because of the size of the presentation I use and the areas I fish I rarely catch undersized lings that require releasing because of regulations.
As far as Hali go I have not picked up an oversized Hali that required releasing since the regulation was introduced. Since I drift fish exclusively and do not anchor up, I do not find deeply hooked fish to be a problem. I have not released too many halibut as most of the areas I prefer to fish have good size fish not ping pong paddles that are being high graded through. Either way, I have not had any problems releasing Hali with this rig either the times I have released them (without any damage in my opinion).
I very rarely ever use a treble hook when Salmon fishing, but commonly do for Ling & Hali. Salmon are easily damaged by hooks, especially the juveniles. Most bottom fish have extremely tough mouths that are hard to penetrate. That is why I prefer a treble. If I were anchored up and letting the fish swallow the bait I would probably not be using trebles. Drifting I find no issue using a treble and safely releasing the fish I catch undamaged.
As long as the regulations permit it I will continue to use trebles for bottom fishing on the drift. I do not like circle hooks, if you do that's great. To each their own.
A sweeping statement that the use of trebles for bottom fishing is "immoral" is a little bit of a zealots response in my opinion. I release far more fish than I ever keep during the course of the season and I consider myself a very ethical angler. I see no moral conflict with trebles in the bottom fishing application (drift fishing) that I use them for. If I were damaging fish badly with them, I would not use them regularly. I feel absolutely no reservations about using trebles for bottom fishing.
You are entitled to your opinion, but I think it is a little extreme in the case of bottom fishing. Cheers, and have a good season enjoying the ocean.