danny,
Baits up in the Water ?
I fish livebaits for Zander in a 20ft deep weirpool on the Lea, I like to have my baits at half depth, so 10ft of the bottom.
And the Crays still get to those baits, you think it's the baits working, but when you wind in the baits, you find a just the Bones of your once Livebait left.
Yes there is a bonus of Big Fish of all species being created by the eating of Crayfish.
But there comes a time when the number of Crayfish in a River system outweights the benifits and The Lea has reached that situation.
It's almost impossible to keep a bait of any type on the bottom for more than fifteen minutes.
Popping up baits is a complete waste of time, hardening baits does little to stop the problem.
The only thing you can do is fish with artificial baits or fish in the depths of winter, when the Crays are not so active.
I don't think there is an answer, as it's beyond solving now.
And for those who think it's only in the south of the country, think again, they are moving North year on year !!
Bob