Buy a have a hart trap and when you trap a squirrel move him about 10 miles away and release him. Eventually, you will have trapped all the squirrels. If they return, and they may, trap them again.
One poster said set up a food and water station for them as if they would leave your pecans alone. Reminds me of the story of a woman who had a problem with deer eating her shrubs. She set out food for the deer away from her shrubs. The deer came and ate the food she put out for them, then walked up to her shrubs and had them for desert.