Hi Irene,
Bitter cucumbers tend to happen with hot dry conditions but the problem doesn't have to be permanent. Try getting at least 1/2 to 1 inch of water a week to them. Mulching them would greatly help in conserving the moisture and keeping the soil cool.The other reason could be the type of cucumber. Burpless and newer hybrid cultivars tend to be less of a problem. Older and open pollinated cultivars can have this tendency.
Most of the time the bitterness will be more intense nearer the skin. Cut off the ends and peel your cukes, wash or soak in fresh water. Pickling will not take the bitterness away. But better growing conditions should help with new cukes.
Best Wishes, Diane