Access digital copies of guides and regulations publications from the Nebraska Game and Parks Commission.
Issue link: http://digital.outdoornebraska.gov/i/720963
21 is one fluke (Paragonimus sp.) that is of concern to humans as it can cause a serious lung infection (Paragonimiasis) if the crayfish are eaten raw. Though rare in North America, a few cases occur every year. 192 A number of crayfish diseases have been discovered but there is little known about their effect on our native crayfishes. Crayfish plague is a serious disease caused by a fungus (Aphanomyces astaci). Apparently this fungus is native to North America and our native crayfishes are resistant so it doesn't cause problems here. However, heavy mortalities of European crayfishes have occurred as a result of the importation of North American crayfish. 53 Finally, while not exactly a parasite or a commensal, some aquatic insects such as water boatmen will lay their eggs on crayfish. "BLUE" CRAYFISH As a rule, our crayfishes tend to be shades of olive-green, brown and red-brown usually in a camouflage pattern. These muted colors and patterns probably help to hide them from predators. But we occasionally see some strikingly different individuals that are a bright blue color. If you did an internet search on "blue crayfish" you would find loads of images of blue crayfish. Apparently, the blue coloration is due to a genetic mutation. ROLE IN AQUATIC COMMUNITIES The crayfish is a detritivore, a planktivore, an herbivore, a carnivore, and all of the above (an omnivore). It is a predator and it is prey. Studies of whether crayfish had an impact on fish populations have had varied results. Some concluded that they did not. 45 Others found that they did. For instance, in a Utah lake, an introduced and rapidly expanding population of Northern crayfish competed directly with Rainbow trout (Oncorhynchus mykiss) for the same food source and trout growth declined. 98 Another study found that fathead minnow eggs (Pimephales promelas) hatched earlier than normal when crayfish began eating newly hatched embryos. 134 If you were a crayfish, the image at right wouldn't be very comforting. It shows that everybody likes a crayfish. . . . as a meal. These include birds (herons, cormorants, gulls, terns, pelicans), small mammals (raccoons, otters, muskrats), many fishes, amphibians (mudpuppy, hellbender), turtles