Check out www.worldwaters.com --> "Tips & Techniques" --> "Myths, Legends, Lies and other Trout Fishing Facts" by Ralph Cutter. I've passed this article along to two other fishing nuts and they agree with my view: it's the best thing we've read in many, many moons.

Don't be put off by the 'Trout' in the title. I'm convinced the points are equally valid for steelhead and salmon. Among other things, Ralph makes these controversial statements:

1. Fish in a shallow river have virtually 360 degree vision, using the underside of the surface as a giant mirror. Approaching fish from the downstream side isn't sneaking up on them at all.

2. Fish can see even light leaders, and completely ignore them. The only reason to fish light vs. heavy line is those times when a lighter leader produces less drag.

3. "Matching the hatch" is nonsense as fish see and respond to colors we see as well as those visible only in the infra red and/ or ultraviolet ranges

4. Loud noises don't scare fish most of the time

5. Fish are not spooked by sinkers or indicators placed near the fly

You may not agree with everything he writes, but it certainly forces you to rethink conventional wisdom.

Snagly, any idea who Ralph Cutter is? Has he published anything else?

I don't know of Ralph other than the website (which he runs) but he is a full-time guide, runs a casting school and has guided/ fished around the world. The people who post on his site think he's pretty good, but someone with No. Cal. flyfishing experience/ expertise would be better able to judge Mr. Cutter's qualifications. (I'm willing to give him the benefit of the doubt.)

But even if Ralph really didn't spend all those hours in scuba gear in trout streams, most of what he writes can be tested very directly -- try it out yourself and see if it works. I'd be particularly interested in reading what happens when heavily fished for trout are presented with natural and artificial flies/ baits that have 1' 15lb leaders glued to them.

Snagly,
I think that Cutter's points, to a degree, are true. Salmonids, of course, are notoriously unpredictable, so any "rule" will apply some of the time. I feel that pretty much any time you can see a fish, it can see you, and that if these fish survive by using their vision to eat and evade predators, I'm sure they can see even the smallest leaders or tippets. The trick is that the fish don't likely make the connection between an angler on the bank and the bait in the water, or make the connection between the line leaving the bait and a problem.
Those of you who know me know that I find the steelhead to be the most worthy adversary in the animal kingdom, so this next comment is made with the utmost respect. Steelhead are not "smart". They are fish with a brain smaller than a pea. The vast majority of that peabrain is used to swim, eat, mate, and run like hell when something is wrong. There is very little, or none, there to make logical leaps or conclusions.
On the other hand, this peabrain is chock full of instinct, which I believe is there from the moment of birth and created from generations of evolution in a particular stream or watershed. This instinct protects fish from predators from above, i.e. birds and bears, or racoons, and protects them from animals stomping through the rivers, i.e., bears and dumb fishermen. I sincerely doubt that if a fisherman is a significant distance from the fish and on the bank, he or she is likely not a big worry for the pea brain, even if in plain sight.
We can all remember times when our most subtle and tricky attempts to con a fish into eating a hook have gone totally unrewarded, seemingly due to a fish that possesses the intellect of Einstein. We can also remember when we've cast out a bait, and the eggs fell off, and the hook caught on the slinky, and you fell in the river at the same time, and a steelhead charged downstream twenty feet to eat the lead/hook/tangle combination and damn near beach itself before you could get your wet ass out of the river (OK, perhaps that last example was a bit over the top, but you get the point).
Moral of the story: Any rule is merely a general guideline, almost any incredible anecdote about steelhead and its actions can be easily believed, and that this is what makes steelhead fishing the most wonderful pursuit that a fisher/hunter can undertake.

Fish on...

Todd.