Baby Sniffers

[hntfsh09]

So I've been spending most of my time this winter ice fishing a pool on a medium-small river in Iowa.  The pool is the largest for miles, straight shot to the big river downstream, and usually a very solid producer for eyes in open water.  A normal fish there would be between 12 and 20 inches.  The pool is 24' deep against a part of the dam, and gradually slopes up on all sides.  Lots of water in the 14-18' range. 

Anyways, 15-17' started producing a ton of activity on the flasher.  Probably averaging a look or two every three minutes, and they definitely behave like walleye.  I have never seen a flasher lit up this much, even going after bluegills.  We are catching a few fish a day, but they are all small.   It will be slow but productive in the few hours before dusk, gets hot for an hour around dusk, and by the time it's pitch black all is quiet. 

So what gives? Are the bigger fish the ones that come up and don't hit, are they elsewhere in the pool? 

A few useful side notes:
I have observed walleye in other stretches of the river that are quite shallow, but they seem insanely spooky.  It seems this 16' of water at least lets me fart without spooking fish. The river is very clear also.
Live minnows are a waste of time (and effort).  Tip ups or slip bobber rigs, even when jigged, have been 110% ineffective.
The fish we do catch have hit everything from small firetiger colored buckshot spoons to big white/glow jiggin raps. They hit on the deadstick, the rise, the pause, the jiggle... There are zero observable trends.

At this point I'm lost. I have marked fish in 12' so my next move is to fish shallower, but initial results on that are the same. Do you guys have any advice for finding the bigger fish/the rest of the fish? I know they are there, but I give up.  Thanks for the help. 

[SDfisher]

I don't fish dams or Rivers, but Id like to think that deep down inside Walter, their behavior is similar across all bodies of water.

My first move would be to scout the water midway, pop lots of holes in the 5-8 foot range right off the main body. look for any abrupt differences in bottom contour.
Rock to mud or sand.followed by old dredging lines that can create an edge effect. Or any small bay openings.

I know u said u tried it without luck, but once you find a few spots like this set out a few tipups with larger than you would think shiners, in the 4 inch range.
One set with a glow jig the other on a bare hook.

Then set up out further and jig, rinse and repeat. until you find a pattern

If all else fails. if they body of water is highly pressured. Skip the evening bite and try the late bite, like 10pm to 2pm. True Lunks adjust to their surroundings and will feed when they feel comfortable.

Just a matter of finding out where their at and when. Hope this helps.