I was in Wally World yesterday, and found these on clearance for like four bucks each. Somehow, one followed me home.

Basically, it is prepacked mini trotline. About 5' long, with about 2" worth of drop for each of the small hooks (smaller than 12) which are spaced about 10" apart. There is a snap swivel on each end. It won't catch anything big, but I'm thinking I can probably rig this without too much trouble and it will catch the same kinds of things as a minnow trap, would be the bomb on small, flocking birds if needed. From the packaging, it almost looks like an ice fishing item, but I'm not sure.

Mine is made by Gamakatsu, item 58109. Can't find it in their catalog.

In the right situation, it will probably work great.

I have fond memories of catching smelt on the Lake Michigan shore front, Montrose Harbor to be specific. We always used nets and caught them by the hundreds at a time fishing from the breakwater. I have never seen anyone catch smelt on a trot-line.

I have used use trot lines / "powerlines" (long story) to catch coho salmon (5 lbs+) on the Lake Michigan shore front too. They are very effective but the hooks were much bigger than size 12.

Are the hooks set up like little white artificial flies?
First, herring are ocean fish that come into inlets to spawn in the spring. Smelt do the same.

Herring rigs are designed to be used during the spawning run. You jig them up and down. Usually a weight gets snapped to the bottom swivel and the top swivel is for your leader.
The herring will strike at the artificial flies,
usually as they flutter in the way back down after you jigged them up.
The herring have small mouths and are less than 16 inches long, more likely about 12 inches. They only eat small stuff so small flies are used.
I have seen people jig them and get a fish on each hook when the run was heavy.
Herring and smelt fishing are best at night when they come near the surface to feed.
I suppose you could fish it for smelt, they are not much different in how they feed.
It is a jig type rig and meant to be fished up and down so I suppose it might work OK as an ice fishing rig.

Smelt under the ice, small trout or perch? Small hooks can catch big fish too.

The only thoughts I am having are if it is not cheaper to just buy hooks and rig your own, and that ganged hooks are illegal in most of the fishing around here.

Looks like a variation of the red snapper rigs I used to use. Might work across a stream or river...

Yep.

We use these to catch bait for Halibut fishing. Nothing gets a Halibut like a live anchovy.
If the anchovy or other type of bait fish are around they WILL hit it. I have caught dozens in minutes when the schools are in.
I have caught anchovy, sea perch, smelts and other small size fishes.

We used to use something similar to catch alligator turtles. The are fairly easily constructed; you just need bait.

That would be the guy.

I'm not planning on catching anything significant with this. "Baitfish" are edible to. :P

I also have caught "gallons" of smelt during the spring spawning run using large square nets off piers in Lake Ontario and with long handled hoop nets near rapids at the inflow of inland lakes. Catching them is lots of fun, cleaning 1000's of them is not so much.

I have never used hooks/line but when the spawn is on the water is filled with smelt and I am sure just jigging the line would catch many.

Mike