That’s actually what I suspected was going to be the case first time I saw the headline but hadn’t read the article yet. I thought maybe someone pre-caught some fish and planted it or smuggled it.
Putting weights in the fish seems risky to me. Most people ought to be able to eye of the fish and give a decent guesstimate of the weight just by looking at it if they’ve been fishing for some time. If they keep winning on weight with fish that don’t look comparatively big, someone’s going to start asking questions.
It’s not just freshwater fishing tournaments, I fished an Offshore Kingfish Tournament in N.Florida one year, the money was so big cheating was almost guaranteed, everything from boats meeting up offshore to exchange fish, to lead weights and everything in-between, the tournment used an X-Ray machine to scan fish to catch lead weights in the belly of the fish.