An ID tag is stuck in the fish near the dorsal fin with a serial number. looks like a piece of heavy mono sticking out of the fish approx 3" long.
The tagger records s/n number, location where tagged, the specifics of the fish tagged and reports the info to a central database.
At a later time when the fish is caught again like the above posting, the fisherman returns the tag with some basic info, location caught, length and weight.
This helps determine a lot about the striper population in general.
Thousands on the boat.
Hundreds on decoys.
Time away from the wife....priceless