Thats not the line that was used to catch it hanging from its mouth, thats what is used to tether the fish for a while so it recovers in the shallows, a rope passed through the mouth and out of the gill opening.
Dragon so you in the fisheries business then mate? I went to Sparsholt when i was a bit younger, out of the trade now though, not enough money

Nice line of work though. Where were you, Yately complex?
Never caught a Catfish, PB Carp is 29lb 8oz though