I like to keep a minnow trap in the water to monitor YOY forage fish just to see what is out there, even if I just dump them back in the same water. The minnow trap will not tell you the quantity because some species will readily go into the trap for feed and others more likely stumble in by accident. But I even get a few RES in them.
I get BG, FHM, GS, GSF, BH, RES, etc. The traps seem to be particularly effective catching small GSF and BH because of their propensity to like feed and their fusiform shape.
...with that said, I believe I will put together a minnow trap, as well...to, like you say, "to see what's out there." Not really concerned with how many YOY I have, predators will take care of the numbers soon...just trying to figure out where they came from and about when.
