In northern Washington state a few years ago, I used chopped beef liver. It's pungent and leaves a good scent trail in the water.
I used traps until I found a better method.
In the late afternoon, I'd chopped the liver into small pieces then throw pieces into three or four feet of water along the shoreline. An hour or two later, I'd go snorkeling with a burlap bag, wearing gloves.
I don't know how hard crayfish can pinch but I had an incident with a scorpion many years ago that makes it impossible for me to pick up a crawdad bare-handed. Silly, huh? Oh well ...
Anyway, I'd just cruise over the beds of chopped liver and pick up the biggest crawdads I found, while they were busy eating liver, and stuff them in the bag.
My buddy and I, using this method, nearly filled a five gallon bucket in less than an hour.
I asked a game warden about our method and he said there was nothing illegal about this method --- but check your laws before trying it.
Drop the crawdads into a big pot of boiling water. Let them boil for a few minutes and then plunge them into a cooler or bucket full of ice water. This sudden change of temperature shrinks the meat away from the shell, making them easier to shuck out the meat.
Enjoy with melted garlic butter, fresh-baked bread and beer or white wine.
Unless you can get a LOT of crawfish, you'll starve to death eating them. Not a whole lot of meat in these critters, unless you get them uncommonly big.
Most of the time, the only meat worth getting is in the tail but a big one will have a fair amount of meat in its claws.
