bump, bump
Bumps, plucks, nips, taps, and kisses on the fly... what the heck is happening? I think that it is most interesting to note those circumstances where they seem to occur with the most frequency.
It seems to me that light touches on the fly take place most often when the water is colder or warmer than "preferred" by steelhead, or when it is extremely clear or very dirty. Also bright levels of light seem to increase the "pluck factor", as well as heavy angling pressure. Fish in the act of moving - pluck - when one is fortunate enough to actually get one interested in the fly. I have also noted that small flies produce more taps than big ones.
Is there a pattern here? Too cold and too warm of water suggest decreased activity levels in the fish for metabolic reasons. Too clear and/or bright light are factors that probably shift a steelhead's primary focus towards concerns of personal security. Dirty water? Another condition that seems to divert a steelhead's center of attention towards I don't know what. Heavy angling pressure is self-explanatory. Moving fish - their attention is completely riveted on getting from point A to point B.
Each of these conditions either dulls a fish's activity levels, or concentrates its "consciousness" onto a primary factor of survival. This in turn either diminishes their capacity for receptivity (metabolic factor) or completely overrides it (survival concern). In other words, under such circumstances a fish's "mind" is not freely "open", "clear" and "uncluttered" to a "notion" for taking a fly as it comes swinging by. Therefore they display less aggressive actions towards a fly, if in fact they do so at all.
On the other hand, I believe that natural conditioning is responsible for the small-fly-more-plucky syndrome. Small prey items are generally not as radical in escape tactics as larger ones, therefore steelhead are probably used to "vacuuming" them into their mouths by flaring their gill covers. As has been discussed before, one's fly is "tethered" by the leader, and thus does not always go "flushing" down into the steelhead's gullet. The result, a pluck or tap, but no fish. However, in most instances (Pacific coast standards), if one does not set the hook - but rather waits it out patiently - the fish will come around for a second, sometimes third try, and will usually have compensated for "missing" (actually the anglers fault) it the first time around.
By the way, Moonlight, the steelhead in Kamchatka do pluck, but it is towards the latter half of the season when water temperatures are on the drop. Earlier on, when temps are in the low 50's, they absolutely CRUSH CRUSH CRUSH!