When life deals you lemons, make lemonade. The guy who formulated that tidbit was probably thinking of one-time nagging little problems. I doubt he had in mind being buried with a whole crop of lemons year after year. But that's exactly what bass face each year with the coming of winter another round of massive lemon drops.
For most bass living in the Northern Hemisphere, the seasonal approach of winter's cold is a fact of life. Bass living in the South, where the temperature drop is mild at worst, may not mind the chill. But for those bass living in the Northern tiers of the United States, the numbing cold of winter spells a time of inescapable hardship. It's another truckload of lemons on the way.
Bass constantly and quickly lose metabolic body heat to the ambient water. Given enough time, the body temperature of any bass will essentially match that of the water around it. To that extent, it is the water, not the bass, that determines body temperature. If a bass wants a higher (or cooler) body temperature, its only recourse is to go find it.
Whatever its final preferred temperatures may be, a bass living at its final thermal preferendum is generally agreed to be in hog city. Here, basking in the mild warmth of its chosen waters, a bass can perform the basics of life while expending the least amount of energy.
That's just dandy, of course, when the bass has a suitable array of choices available to it. Unfortunately, for most bass populations, life's reality is that we seldom get what we want when we always want it. There are always those periods, especially with the advent of winter, when life throws in those lemons.
As winter sets in and the water temperature starts to fall, a bass' first line of defense is to seek out whatever warm waters are available. Early on this may be easy. Most natural waters are inherently heterothermal, so unless a bass already lives in the hottest spot, there is a reasonable chance of it finding some place warmer. This may occasionally require crowding into less desirable areas, places where the bass has limited food or where it must expose itself to greater risks.
But finding warmer water is a short-term solution at best. As its body temperature falls, a bass is genetically programmed to remake itself chemically. Generally, an 8° F drop in body temperature is enough to cut biochemical reaction rates in half. The bass still appears active, agile, and quite responsive to live prey and lures. But it's only a matter of time. With each degree drop in temperature the bass metabolism, already taxed, begins to falter.
For bass, movement through the cold, dense water can be a real chore. Brief periods of moderate activity are interspersed between much longer periods of lying still on the bottom. Chasing food long distances is largely out of the question. Most of their strikes are limited to short distances and on smaller prey.
Bass anglers can take heart, however, in the fact that even at these low temperatures bass fishing does not cease altogether. For those stronghearts who can brave the cold, the more active bass will still feed on the lures. The general rule of thumb is to keep the baits small and fish s-l-o-w-l-y.
With the return of warm water, bass are again ready for a good scrap.