I don’t think guides harm the resource to a significant degree overall, but if you are considering reducing impacts to prevent a listing or allow a fishery to happen, why not start with the people that are professionally targeting the fish? The people who may be from literally anywhere in the world and who are here to make money on the resource?
I don’t get how you write off being for curtailing guiding as being about catching more fish for recreational anglers, like it’s a self serving stance. I know lots of folks that don’t use guides and catch plenty of fish to be satisfied. We all see what it’s like on the few remaining steelhead rivers and how the guides move in and set up shop. In some cases the sense of ownership and entitlement among guides shows how unchecked they are. Sports fishing doesn’t exist for guides and it doesn’t exist to make people money guiding. It exists to have fun and connect with the natural world. It is such a USA thing that something that creates jobs and economy goes nearly unregulated and harms something pure and meaningful like sports fishing. I do think that commercial fishermen and guides will be the last ones fishing (see the post about heavily regulated waters in Montana above), and that is fucked up.
There are a number of fishing regulatory measures to select from. What ones to use depends on the fishery management objectives. I think WDFW's Skagit steelhead management objectives go something like this:
1. Least overall hassel to WDFW (Washington Department of Salmon);
2. Stay at or below the allowed ESA take number for the given year;
3. Some opportunity for the greatest number of anglers is preferable to lots of opportunity for fewer anglers.
There are a number of management tools to ensure that ESA take stays within the allowed number.
1. In the best of all possible worlds fish are abundant, so the season is long and fishing restrictions are minimal;
2. In the world of ESA listings, managers consider fishing method and gear restrictions to limit impact on the fish population. That's how we ended up with the Skagit CNR season with the Special Rule and Gear restrictions in the first place back in 1981. Those included:
A. No fishing from a boat equipped with a motor while under power;
B. No bait;
C. Single barbless hook only.
If that doesn't keep "take" within the allowable limit, I think the further considerations are restrictions based on relative effectiveness of fishing methods or a lottery or an auction. In general, boat anglers are more effective than wade anglers; conventional gear anglers are more effective than fly anglers. It's very possible that guided boat anglers are more effective than non-guided boat anglers, but I don't think the Department has data for that breakdown. If it is necessary to further reduce incidental take, a logical management action could be to limit fishing to no fishing from a boat and fly fishing only. And since most steelhead fly fishers use 2-handed rods these days, it could be further limited to maximum rod length of 9'. Of course these more restrictive measures don't satisfy WDFW's management objectives #1 or 3, so the preferred choice is to simply close the river to fishing.