This basically sums up the first two places Noah and I fished yesterday.
Where there had been huge schools of fish just days before there were none. A cove with brush filled with perch eggs and fish eating birds seemed to be a ghost town underwater. Where the hell did all the fish go?
The thing with large river systems is that fish can just leave an area altogether. Pack up and take a hike. A place that was teaming with life yesterday may have so few fish today you can't even get a shiner in a cast net.
The thing is with small ponds...
They can't do that. So off to some small ponds Noah and I went, where we caught pint sized versions of a few species. Happily one carp took pity on me and slurped down my dry fly, so despite it being a very small carp I still got a good fight in from what was really a day of fish in miniature.