Repetitive motions and grips with your hands can lead to carpal tunnel syndrome. After years of working in the trades, pulling on wrenches, and gripping a fishing rod, my hands/fingers were numb all the time. Last summer I couldn't take it anymore and had surgery on my right hand. Much better now! If it continues, try wearing a wrist brace while fishing. It may not be fashionable, but it will keep you from bending your wrist, compressing the nerves in your wrist, causing the pain and numbness.