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Bass Biology
Bass and Their Eating Habits
By Wayne Gustaveson

May/June 1995

Ever had one of those days in early spring when the pre-spawn fish were behind every rock, under every ledge, and just could not wait for your bait to hit the water so they could swallow it? For me there have been more occasions when the fish had their mouths shut tight, heads jammed under a rock, and there was absolutely no interest in my perfect casting technique or the absolutely irresistible purple and chartreuse whiz bang on the end of my line. What makes the difference? The scientific name for the study of this phenomena is etiology or the wonderful world of animal behavior under natural conditions.

Trying to understand why fish do what they do is only slightly easier than trying to get one to talk. You can put the fish on the psychiatrist's couch but just can't make him comfortable enough to express his inner feelings. We will never know about his relationship with a parent that left him as an egg on a gravely shoal and never once returned to check on his welfare.

Our next best option is to stand behind a one-way mirror and try to learn about behavior by trial and error. Bass anglers are incredibly apt students in the study of what fish will take into their mouths under a varying set of conditions. That's what they do. It's called fishing. Biologists try to refine this to include the study of characteristics that do not necessarily relate to setting the hook. But some of the things that have been discovered may also be useful to the study of bassology.

For instance, fish feed when they are hungry and/or when instinct dictates. It is well known that bass and sunfish coexist most of the time in a peaceful, blissful state. Periodically, bass get hungry and "announce" that it is now dinner time. That event begins with a rocking motion of the body followed by a flaring of the gills and culminates with ingestion of the nearest neighbor that will fit into the mouth.

The gill-flaring action reminds me of a healthy yawn. Sunfish that have been rubbing shoulders with bass for most of the day will immediately scream and run for cover when the gill-flaring behavior is seen.

Bass also feed instinctively. A passing object may trigger a reflex action which results in feeding behavior. So those great days when fish were caught behind every rock probably coincided with an extended feeding period. Catching a fish here and there on the same type of "pattern" means that instinctive feeding is occurring. Finding a lure, presentation, and a location may instinctively cause feeding under a repeatable set of circumstances.

Bass do not feed continuously. Only 50% of fish sampled at any given time are empty while 50% have something in their stomachs. They do feed at night as well as daytime hours. They seem to be less wary during twilight periods and feed more consistently when light is subdued (I'll be you already knew that!).

As a general rule most bass are homebodies. Smallmouth bass are especially stationary, spending most of their life within a range of 200-400 linear feet. In tagging studies, it has been found that most recaptured largemouth bass were taken within 300 feet of the release site. Bass in your lake will behave differently depending on the individual circumstances that exist.

It has been found that both largemouth and smallmouth will move greater distances when shad are present. It makes sense that bass will travel further to capture the highly digestible and very mobile shad than they would if the only baitfish available lived in the same bush as the bass.

Fish do rest. Smallmouth bass will place their chin on the substrate with the tail slightly elevated so nothing touches the chin. They may remain motionless in this attitude for a few minutes of as long as a day or two.

Each population has fish that are wanderers and fish that are content with a given spot. Those that wander are probably young fish looking for the perfect spot. Dominant fish stake out the best spots and protect their lair by butting, biting, and intimidating smaller fish. Yes, that does mean that once a big fish is removed from a spot it is likely that the next dominant fish will occupy the territory. But if the big fish is put back he will find his favorite hiding place and be there when you return to battle him again.

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