Been away from the pond for a couple weeks but threw in three traps late this afternoon. The standard opening (1") minnow traps did not have much in them in the hour or so they were in the water. They will probably need to go over night and I will check them tomorrow. But the trap I have enlarged the opening to 1.5" had a good number of GSF in it fifteen or twenty minutes later. A standard 1" opening minnow trap will trap GSF up to about a maximum of 3". The 1.5" opening trap I caught several in the 3-4" range.
Some notes about enlarging the opening in a minnow trap. By making the hole bigger they will catch larger fish (duh). But the fish can also swim back out much easier. The 1" trap will hold fish for quite a while. The 1.5" opening really needs to be checked before all the feed is consumed or the fish will find their way out pretty quickly. If I do a half hour check the wide opening trap will have more fish than the smaller opening. If I leave both traps over night the larger opening might have one or two fish and the smaller opening will have lots of fish. Just be aware the bigger the opening the bigger fish caught but also the more often it needs to be checked and re-baited. One other note is most states specify that a 1" opening is the maximum legal size opening for use in public waters. So if you enlarge the opening on a minnow trap it may no longer be legal to use it in public lakes and streams. Just be aware of that.
Picture below is of a Gee's trap that the opening has been enlarged to 1.5" (from the standard 1") and the catch of GSF out of my forage pond.
Also be aware you can only trap fish in the size they exist in the pond. If your YOY fish have grown enough they are too large to enter the opening you are going to catch few fish. The trap opening size has to match the target size fish.
