What it is
The stick float is running-water fishing. A buoyant top, a cane or alloy stem, shot down the line, and a bait that trundles the crease as if it belongs there. You hold it back to lift the bait, let it run to search, and mend the bow so the float doesn't drag off line.
It is a 16 June method on rivers, streams and drains in England and Wales. The close season is 15 March to 15 June inclusive. Canals that are still canals are usually fine; if it looks like a river in a straight jacket, check.