Winter Bass - What They Do

By Russ Bassdozer

Everyone wonders what bass do in the winter? Curiosity got the best of me too, and I researched the issue. Here is a little more about it. It primarily pertains to bass in colder northern ranges.

Biologically, bass and many other game fish are programmed to fatten up during late fall in instinctive anticipation of a scarcity of food as winter arrives.

As waters drop in temperature in winter, there is less food available to eat. For example, a surprising number of species of crustaceans, mollusks, reptiles, amphibians and insects all vanish into the mud or elsewhere underground until spring. Other prey sources become less dispersed and less available to predators as winter approaches as well. This reduces the total "energy content" available in the water - and consequently less incentive for bass to pursue food. Instead the bass will swim less, eat less and otherwise conserve the "energy budget" it has stockpiled within its own body. As the water gets downright colder, food gets even scarcer, and the bass tend to fast for long periods of time in cold water. This inactivity happens gradually day by day and eventually causes its muscle composition and body chemicals to change so that in deep winter, it could not swim fast or otherwise act as a quick swimming predator in cold water. Even if it wanted to, it would be impossible to swim quickly to pursue bait such as a minnow.

A small item of interest is that a few minnow species are known to have an actual "anti-freeze" chemical in their blood which allows them to remain slightly more active, and therefore more elusive to consistently avoid being caught by the slowed-down predators during the winter.

In extremely cold water, bass even tend to lose their balance and may even have difficulty in propping themselves upright on the bottom. Keep in mind that this loss of swimming ability is a gradual process over an entire season of winter in cold climates. The bait has to become scarce over time, the bass has to become inactive and stop pursuing bait over time, the water has to increasingly become colder over time...all these changes take place over time. So, if there is a quick chill and quick water drop in early winter, you can continue to find plentiful bait and plenty of feeding bass in chilled waters in early winter. But, given time, the whole cycle of reduced energy content (less food in the water), energy budgeting by bass (less incentive to feed), and consequent reduced swimming ability will happen to bass in colder climates by deep winter time.

In a late winter, when the water stays open (no ice) longer than usual, fish may continue to follow the instinct to feed later into the season than usual. This is generally not good because the low water temperatures restricts the rate of food absorption which also limits the energy intake derived by even a "well-fed" bass. Often, gastric evacuation results (puking) rather than digesting the food and unlocking its energy. In this way, the energy "cost" of maintaining a high metabolism for continued feeding is far more costly than the energy gained from it. Therefore, such continued feeding only begins to deplete its stored body reserves in order to "pay for" the continued loss of energy from the fruitless continued feeding. This breaks down the condition of the fish and compromises its ability to endure throughout the still long winter ahead.

This affect is especially serious in young of year fish that simply do not have the body mass to "budget" large quantities of energy that will carry them over the winter. They will, however, be fine if a normal, cold winter slows their metabolisms to a very low level that allows them to subsist in a sort of suspended animation. For young of year fishes, a good cold winter is generally survivable. In fact, it has been reported that young of year of some species have been known to endure being frozen solid within ice at times during the winter...and they apparently thaw out with no problem. This resiliency is only present in the smaller young of year...and larger fish that are frozen do not have the same durability to thaw out and swim away so happily.

However it's probably an extreme case for them to get frozen - I think that they mostly go into something like a suspended animation-like state to winter-over. I think this is a good way to think of it. This is a common pattern in nature, for animals to endure and in a certain sense "cheat" winter by going into a "deep sleep" and not waking up until spring. Besides, if you have ever seen bass during other adverse times of weather (cold front, hot water), they are definitely prone to "zone out" not just in winter, but they often become inactive and drop into a stupor-like state at any time of the year when conditions are not favorable to them, not just winter. Anglers generally say the bass are "inactive" then - whether it's for a few hours, a few days or even weeks. No doubt, the bass have shut down their high-maintenance body systems in order to budget their energy and wait for more favorable periods of time. This is not a conscious thought or decision made by the bass, but Mother Nature at work controlling their metabolisms to ensure their short-term vigor and long-term survival of the species.