It will stain even in fresh water but salt water will accelerate it. You have to understand that the only thing between the bare metal and the harsh salt is a thin film of wax. That said, your pole has absolutely no protection on it at all. So the staining you are seeing is actually the preliminary stages of corrosion. You can try to clear coat it but because of the waxy surface, it may or may not stick. You can get a chrome powder coat as well but it's not real cheap.