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The Crayfish of Ohio,

An Angler's Guide to Mudbugs!

By Dave Votaw, Photos by Joe Cornwall

 

So you’re a smallmouth bass fisherman and you think you know crayfish, right?  And I’m not talking about that plate of mudbugs you had at the local Cajun bistro last week.  We all dissected a crayfish in high school biology; I even took invertebrate zoology as a college undergraduate, but nothing prepared me for what I found when I decided to revisit this subject recently, a subject dear to the heart of every smallmouth bass fisherman.

 

We humans can get excited about almost anything imaginable, so welcome to the world of astacology, the study of crayfish.  Astacologists love their crayfish more than we can imagine; just listen to Dr. Keith Crandall, Department of Integrative Biology, BYU:

 

“Freshwater crayfish are a beautifully diverse group of organisms with over 605 described species of freshwater crayfish distributed throughout North America, Australia, southern South America, Asia, Europe, Madagascar, and New Zealand (summarized at http://crayfish.byu.edu).  They come in a variety of sizes, from the members of the dwarf crayfish, Cambarellus (reaching lengths of only 2 cm as adults, to the world’s largest freshwater invertebrate, the endangered Astacopsis gouldii (reaching lengths over 40 cm and weights over 5 kg).  These beautiful organisms come in many colors, including red, blue, orange, green, brown, and even pigment-less (white).  There are crayfish with spots, stripes, and patterns of various sorts.  They are truly a splendor of morphological variation.  Indeed, they also have some ecological variation, inhabiting four main habitat types, the fast flowing streams, primary burrowers, pond/lake/slow water species, and the troglobitic (obligate cave) species.  It is presumably this ecological diversity coupled with extreme isolation for most species (at least 15 of the 605 species of freshwater crayfish are only known from a single location and most species have very narrow geographic distributions) that has lead to the grand morphological assortment of species.  Because of this diversity coupled with a relative ease of collection and their conspicuousness in the ecological community, freshwater crayfish have served as a modle organism of study in a variety of sciences. [Crandall K. 2006. Applications of Phylogenetics to Issues in Freshwater Crayfish Biology. Bull. Fr. Peche Piscic. 380-381:953-964.]

 

Crayfish are the largest mobile freshwater invertebrates and have long been of commercial and scientific interest; they have been used in research on the role of vitamin A in vision.  They are of such interest that an organization known as the International Association of Astacology (http://iz.carnegiemnh.org/crayfish/IAA/) exists, including membership, conferences, symposia, publications, even a crayfish forum for collectors.  Some of these folks keep crayfish as pets, although my personal experience tells me it isn’t possible to keep more than one in an aquarium, at least not for long; crayfish find one another just as tasty as we find them! 

 

Crayfish reach sexual maturity early in life and mate in the fall; fertilization however is delayed until spring when the eggs can be seen on the ventral side of the tail attached to the swimmerets, a condition known as ‘in berry.’  Hatching of the egg mass is dependent on water temperature and can take up to 20 weeks.  The young remain with the mother through 2 molts until they are big enough to subsist independently.  Juveniles can molt as often as every week, although adults may molt only a few times per year.  Seasonal growth and molting begin when water temperatures reach about 40º F in the spring and end when temperatures drop below that mark in the fall.  Average life span is 2 – 3 years.  Crayfish are omnivores and will eat almost anything, plant or animal, live or dead.

 

Crayfish are of course crustaceans from the order Decapoda, meaning 10 appendages – 4 pairs of legs and 2 pincers on the cephalothorax.  The name ‘crayfish’ comes from the French ecrivisse having the same etymological root as crawl, and is today the French word for crayfish.  North American crayfish are classified into 2 families, Astacidae in the west, and Cambaridae in the east.  The following is the crayfish species checklist for the State of Ohio:

 

Cambarus bartoni cavatus – Appalachian brook crayfish

Cambarus carinirostris – Rock crayfish

Cambarus diogenes – Devil crawfish

Cambarus ortmanni – Ortmann’s mudbug

Cambarus robustus – Big water crayfish

Cambarus sciotensis – Teays river crayfish

Cambarus thomai – Little brown mudbug

Fallicambarus fodiens – Digger crayfish

Oronectes cristavarius – Spiny stream crayfish

Oronectes immunis – Calico crayfish

Obscurus obscurus – Allegheny crayfish

Oronectes propinquus – Northern Clearwater crayfish

Oronectes rusticus – Rusty crayfish

Oronectes sanbornii sanbornii – Sanborn’s crayfish

Oronectes sloanii – Sloan’s crayfish

Oronectes virilis – Virile crayfish

Procambarus acutus acutus – White river crayfish

Procambarus clarkii – Red swamp crayfish

 

This summer Joe Cornwall and I collected a few crayfish and drifted their tails under a float in one of the local creeks just to see what would happen.  I knew what the result would be; every species of fish in Midwest creeks will eat craw tails; they are all I used as bait when I started fishing as a kid.  Ohio fishermen can possess up to 100 crayfish at a time for bait.  And as Dad used to say when we set off with a bucket of crawdads for a day of wading, “If we don’t catch anything, we can always eat the bait!”

 

More information can be found at the Crayfish Home Page:  http://crayfish.byu.edu/index.htm

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