How Water Temperatures Affect Largemouth Bass Behavior and Metabolism

Water temperature is one of the most significantexpend less energy capturing and digesting food,
factors to rely on when trying to locate and catchwhich enables them to be more efficient in cold
largemouth bass. As water temperature changeswater.
throughout the year, so does fish behavior andAt 39° F, which would occur mostly in northern
metabolism. Learning to identify how lakes changelatitudes where ice cover is possible, it is theorized
and how largemouth adapt to these changes canthat largemouth bass may only feed a couple of
improve your success on any body of water.times per month during the winter, and each meal
Fishing for largemouth bass during the hot summertakes between 14 and 17 days to digest. Therefore,
months is often frustrating because warm waterlocations that consistently produce notable catches in
temperatures can make finding and catching fishlate fall or early winter are likely to be where large
difficult. Periods of seasonal transition, however, areaggregations of largemouth bass can be found until
typically excellent times to track largemouth bassthey "migrate" to spawning grounds in the spring.
based on water temperature. One such time is earlyHowever, only a few will be caught on a daily basis
fall when air temperatures begin to dip into thedue to their slow metabolic processes and feeding
70° F range. In ponds and lakes, this initialbehavior in cold water.
cool-down period is a precursor to fall turnover.Fish must use the energy from a single meal to meet
Pre-turnover water temperatures instinctively cueseveral needs. Carnivorous fish, like largemouth bass,
fish that winter is coming and feeding activityhave an energy budget that differs from herbivorous
generally increases.fish such as grass carp. Approximately 20% of the
What is fall turnover? It's a process that breaksenergy gained from what largemouth bass eat is
down the stratification, or layering, of warm surfacediscarded as waste, 15% is used for activity or
waters above cool or cold deeper waters thatmovement costs, 14% is applied for digestion, 7% is
occurs in lakes during the summer. During theused for standard metabolic processes, and the
summer, mixing only occurs in the uppermost layer ofremaining energy is split between growth and
water. Most folks that have been swimming in a farmreproduction.
pond during the summer have noticed thisOne thing you must keep in mind when fishing
stratification...your upper body feels nice and warm,transitional periods (drastic or seasonal changes in
but your feet are ice cold. Fall turnover occurs aswater temperature) is that largemouth bass are
surface waters cool, become more dense thanadapting to climatic changes. Accordingly, anglers
underlying layers, and sink, thereby pushing themust also adapt their fishing patterns and techniques
underlying water layers to the surface. This mixingif they expect to consistently find and catch
action occurs until all water is the same temperaturelargemouth bass.
(isothermal) from surface to bottom.It is key to pay careful attention to aquatic
Fall turnover of a stratified lakevegetation during the fall to winter transition in lakes.
In most lakes and reservoirs, as water mixes fromObserving the state of vegetation, whether heavy
surface to bottom, it is likely to become less clearor sparse, green or brown, or deep versus shallow, is
and odorous from gases trapped in the bottom mud.helpful in locating and catching largemouth bass. For
Dark, dead vegetation is another clue that fallexample, aquatic plants become sparse in shallow
turnover has occurred.water, which will cause largemouth bass to seek
The body temperature of a largemouth bass is thevegetation in deeper water on protected breaks and
same as the water where it lives. As a result, itson inside bends near large flats. As winter
metabolism and body chemistry change as waterapproaches, all vegetation in the shallow portion of
temperature changes. An abrupt decrease or increasethe lake has begun to turn brown and die.
in temperature of 8 degrees or more can causeOccasionally, largemouth bass will cruise these areas
internal chemical imbalances in fish. It's important toon warm, sunny days, but, more often they are
realize that when largemouth bass experienceforced to hold on steeper drop-offs among rocks or
changes in temperature, they may become inactivestumps.
until their bodies can reach equilibrium at a newAnother important factor to consider is wind direction
temperature. It may take largemouth bass severaland time of day. During the pre-turnover period,
days to recover from a decline in temperature,when largemouth bass tend to school and feed
whereas they can recuperate from an increase inheavily on baitfish, anglers often target the windy
temperature in only a few hours. Therefore, coldbanks because baitfish tend to be concentrated in
fronts have a greater impact on fishing than warmthese areas. However, on cool days in late fall or
fronts.early winter, this may not be the best strategy.
Largemouth bass will instinctively move to warmerWhen there is a little "chop" on the water, light, and
water when the water temperature is belowthus heat, do not penetrate the water's surface to
76° F and to colder water when above 86°any considerable depth. As a result, areas affected
F. A largemouth bass can detect changes in waterby wind may become less attractive to largemouth
temperature less than one half of a degree using itsbass. In areas that are as flat as glass on cool days,
lateral line. In spite of this, bass will not normallylight, and subsequently heat, can stimulate inactive
search for locations that offer optimumfish to feed more readily. Largemouth bass are
temperatures if all of their basic needs are being met.typically more active during the middle or warmest
Even though they are most likely to move to feedpart of the day in fall and winter. As a result, you
or avoid life-threatening conditions, no single factor ismay have success fishing for largemouth bass on
dominant enough to force bass to move away fromlarge flats or in shallow coves adjacent to deeper
satisfactory conditions in an effort to achievewater during the warmest part of most autumn days
optimum conditions.or during sudden warm spells.
Cooler water temperatures slow the metabolism ofAs discussed above, water temperature directly
largemouth bass, which causes them to limitaffects the bodily functions and behavior of
movement and eat less. Even though the metabolismlargemouth bass in many ways. When water
of largemouth bass slows in cooler water, this doestemperature is actively changing, bass will adapt
not mean that they cannot swim fast or aggressivelyaccordingly. For consistent fishing success, therefore,
strike a passing lure. However, smaller prey such asit is vital that anglers understand how and why bass
aquatic insects typically offer less resistance tobehave as they do at various temperatures. It's also
capture, take less energy to digest, and are oftenvery important to know, not only the water
targeted by largemouth bass when the water coolstemperature at the time you are fishing, but also the
to around 50° F. Even at this temperature ittemperature trend in the days preceding your trip.
may take between 4 and 7 days for a largemouthDoing your homework on water temperature
bass to digest a single meal. This strategy ofdefinitely increases fishing success.
consuming small prey items allows largemouth bass to