I recently went to Sagehen reservoir and caught several fish that had living bugs embedded in their skin. Are they safe to eat?
Yes, remove the skin from the fish and they'll be fine to eat.
What you see on the skin of the fish are copepods, or often referred to as "aquatic lice." They are present in almost every waterbody in Idaho and usually become active when water temperatures warm-up in June through August.
If you look at the copepods under a microscope you will see jagged hooks they use to attach to the outside of the fish. Eventually, if they remain attached, will form an ulcer on the skin of the fish which can become infected. Most of the time, water temperatures cool before the wound becomes fatal to the fish, and the copepods fall off.