Article by: Jimmy Yarbrough

Many anglers ask the question, “Just what do bass eat?” Knowing the specifics to that question can be a key to catching more fish. In different parts of the country and in different seasons of the year, bass feed on different forage. Understanding what they eat and when can make you a more successful angler. Bass are opportunistic feeders and won’t pass up a good meal if it falls in their faces, but they do have distinct preferences in forage size, color, movement, smell, and sound. Let’s begin our survey of bass forage with one of its most misunderstood food sources.

The Crawfish

A favorite food of all bass species is the crawfish or crawdad in southern terminology and crayfish to those that live up north. Crawfish are close relatives of lobsters and crabs. They are found throughout the world and provide an important food source for many animals. Most live in freshwater, but a few species live in brackish or even saltwater. Most bass anglers know very little about their habits and life cycle.

Appearance

Crawfish have a joined head and thorax region called a cephalothorax and a large tail section or abdomen. They have two pairs of antennae with one pair much larger than the other. They use their antennae to pick up vibrations in the water, helping them to locate food or avoid predators.

Crawfish have 5 pairs of legs with the front pair being modified into large pinchers. The large pinchers are used to catch and hold prey and for fighting each other or predators. The legs will regenerate if broken off. The hard exoskeleton is made of calcium and protects the internal organs from danger. To grow, a crawfish must shed its exoskeleton. This is called molting. Young crawfish molt every few weeks, but this process slows down as they reach adult size. After molting, it takes several days for the new exoskeleton to harden. These “soft-shell” crawfish are more vulnerable to predators and spend a lot of time in hiding. They eat part of their old exoskeleton to regain lost minerals and also have calcium stones stored in their stomachs that are absorbed to help harden the new  exoskeleton.

Colors

Crawfish coloration is what most anglers are interested in and studying local crawfish is a good idea. There is tremendous color variation from species to species and even within a species. Very little scientific study has been done on crawfish coloration. These color variations are not by chance, but determined by their environments. Colors range from brown, tan, green, red, blue, black to sandy yellow and combinations of all these colors. A lot of crawfish in our area are brown or tan with orange pinchers. Another common color is black with metallic green mixed in, strongly resembling a junebug color.

A number of factors influence crawfish coloration. When crawfish move from location to location, they can change their coloration to match their environment. This change doesn’t occur almost instantly like in a chameleon, but takes hours and days to weeks. The potential for rapid color change could occur after molting. Dr. B. A. Hazlett of the University of Michigan found that a particular species of crab existed in two color patterns or morphs. One morph was reddish-brown and the other green. Individuals were observed to molt from one morph to the other depending on diet.

Apparently water chemistry and pH also play a role. Crawfish have red and blue photoreceptors, which collect light from different wavelengths. In a Michigan study, Dr. Robert Thacker found that crawfish in water where blue-green wavelengths transmitted best were lighter in color. Crawfish in water where red light transmitted best were darker in color. As you can see there are a lot of variables that influence crawfish coloration. The best way to determine the color of
your local crawfish is to set out crawfish traps. These are inexpensive and readily available. Bait them with carrots, hot dogs without red dye, English peas, or pieces of potato. Put them out late in the afternoon and check them the next morning.

Crawfish Fallacies

There is a tremendous amount of misinformation and folklore about crawfish. Over the years I’ve heard anglers say crawfish go into hibernation when the water temperature goes below 50. Crawfish do not hibernate. The crawfish pictured with this article were collected in water with a temperature of 40. Being cold-blooded, they slow down in cold water, but they don’t hibernate. Burrowing species become trapped when the water at the top of their burrows freezes and prevents them from reaching the surface. Another fallacy is that crawfish molt and release their young according to moon phase. My experience is that age, water temperature, and food supply affect the crawfishs’ growth and thus its need to molt. Water temperature affects egg maturation and the molting of baby crawfish. I have collected soft crawfish under all phases of the moon and captured females in berry throughout the spring and summer regardless of moon phase.

Bass Predation

Bass eat crawfish year round, but seem to show a definite preference for them in late fall and winter. Crawfish are very rich in proteins and an excellent food source for bass.

Another time when bass feed heavily on crawfish is when warm rains flood highland reservoirs and bass can move up onto flooded tributary streams and reach crawfish not normally available. In Dr. Thacker’s study on crawfish he looked at crawfish predation by both largemouths and smallmouths. Most readers could probably guess the results. Smallmouths consumed a significantly larger number of crawfish than did their largemouth cousins.

Learning more about what bass feed on and the behavior of that prey will make you a better angler. Spend a little time studying prey behavior and coloration and the results could be a lot more bass on the end of your line.