Interesting. Never seen that. But then, the crayfish I caught were from cold, clear waters in Washington and Idaho.
It might be gross, but a potful of boiling water will take care of any parasites in short order, as far as any menace to your own health goes.
Some 30 years ago, at my lake cabin in British Columbia, Canada, we noticed long, round worms at the joint of the front fins (pectoral) on the Rainbow trout we caught.
The parasite didn't affect the meat, we found through examination. We figured it would be seen more often and dreaded the thought. Only saw it that one summer. Never saw those parasites on fish again.
I've often wondered if some dumbass didn't bring in some kind of baitfish and they escaped into the lake, bringing parasites with them. I suspect that the brutal winter (4 feet of ice on the lake) interrupted the cycle of those parasites.
Have you had an unusually mild winter? Or inordinate amounts of water? Perhaps this was just one of those seasons that allowed the parasite to thrive. Perhaps next season it will be held in check naturally.
Who knows? Report what you found to the Fish & Game office. Save a crawdad in the freezer for their lab. This may be something new, introduced by an outside species, and you might be able to give them an early heads-up to fight it.
