Crays will always be present at the lake as we are located on an island. I have fished around the world for carp for over 30 years and can definitely tell you that they really aren't a major problem! Crayfish are important in the fishery as they eat fish eggs which in turn stops the lake being over run with small fish. They also help clean up the silt and detritis.
1. use netting or shrink wrap around your hookbait
2. use a very strong thick hooklink that wont get rubbed and cause losses.
3. use more bait and re bait every 4-6 hours.
4. use a hair extender stop rather than a flat one