Freezer Burn
Sounds like it's freezer burn. They get white spots when the skin dries out. I've read a few threads about this on here. Most people say to go ahead and feed them that the nutritional value is still okay. Others don't like the idea. So I guess it is kind of personal preference. I personally wouldn't feed them unless I had no other option, but that's just me. I know I don't eat meat that has freezer burn! But you can always check out the other threads: I did a search for freezer burn and white spots.