A. I looked up what I could find about crayfish coloration; the following information is from Pennak's "Freshwater Invertebrates of the United States," 3rd. ed. He says that crayfish normally range from blackish through brown, red, orange, green and occasionally blue. He further states that newly molted animals are usually brighter in color than those who have accumulated silt, dirt, and other material to dull their color. Often, crayfish closely mimic the color of the substratum where they are found, but this obviously takes time to develop.

Thus, although you obviously haven't seen many blue crayfish in your region, this color is not unusual.