Water Temperature and Bass


Modern day bass boats have more electronics in them than the cockpit of advanced tactical fighter planes or so it seems. There are devices to gauge the water’s pH level, and even the amount of light filtering through that helps determine the color of the lure one should use. Some boats are equipped with barometers and air-temperature gauges. Many even have stereo units that will put your home system to shame. But the most overlooked electronic equipment on most bass boats is the easiest to operate and is, literally, the most important instrument. This tiny meter can tell you where bass should be, and how deep they’ll be holding; when bass should be most likely to feed and the most active. It can even recommend the types of lures you should tie on and how they should be fished. No, it isn’t some new space-age mystery device that gathers data from satellite downlink. It gives you, quite simply, what you need to plan your bass-fishing day, water temperature. Talk with the country’s best bass anglers. They’ll all tell you the same thing, namely, knowing the water temperature and tracking temperature changes is the information they find most useful. And while water temperature, pH levels and oxygen content are all interrelated, it’s the temperature that can be most easily determined and used. More research has been conducted on water temperature and bass behavior than any other in the fish’s lifestyle. When the temperature goes up or down, anglers can reliably predict what bass will do. It’s a variable that can be reacted to in a set way.
Why Water Temperature? Bass, like all fish, are cold-blooded. They depend upon their environment to provide them with adequate warmth so they can live comfortably. As water temperature rises and falls, bass change their lifestyle to match conditions. In colder water, for example, their metabolism slows and they become less active. When the mercury rises, so does their metabolism; they become more active and aggressive. Water temperature is also closely related to water oxygen content, another key in bass behavior. Without adequate oxygen in its bloodstream, a bass will slow its activity level. With increased oxygen, it becomes spunky and active again. For the average bass anglers, however, measuring water temperature is much easier than oxygen levels. Knowing the prevailing water temperature will tell an angler a lot about the lake’s oxygen content without his worrying about measuring it.
Using Water Temperature: When trying to locate fish, many anglers use water temperature as a litmus test for bass behavior on a seasonal basis. However, it can also be used on a day-to-day, and even hour-to-hour, measure during some seasons. Generally, when the water temperature rises into the mid to upper 50s Fahrenheit, sluggish bass begin moving out of deep water into more shallow depths in preparation for the spawn. They use both the water temperature and the photoperiod – the amount of daylight on a given day – as their key indicators that it’s time for spawning. Most biologists agree that a water temperature between the low 60s and 72 degrees is when bass remain in the shallow-water flats to begin spawning. As the spawning cycle ends and water temperature levels stabilize somewhat during late spring and early summer, most bass move off the flats and into relatively deeper water, where they spend the hottest days. A few bass will always live in the shallow flats areas, but most move deeper. As summer ends and fall arrives, water temperatures cool down a bit and many bass again move into shallow-water structure areas before heading to the deep water they call home in winter. Knowing the water temperature will help you locate bass at any given time. It can also help you find the most aggressive fish-the ones easier to catch. In spring, for example, as the water warms, look for likely prespawn areas near protected northern coves and creek mouths. Water warms in these areas earlier than all areas on the lake. It’s because of the way they catch the sun’s rays, and because creek water flowing into a lake in spring is warmer than the lake itself. In these areas, the bass’s food-chain creatures will also be the most active. By following this pattern around the lake as the prespawn period develops, you’ll be fishing a lake’s more aggressive bass. The key, then, in early season is to follow, and fish, the warmest areas of the lake. During the post-spawn period, however, look for those areas in which the water temperature warms up later than it did in other areas. In these areas, you’ll still find active, aggressive bass. Other areas that had good action early in spring are in a sluggish summer mode. In summer, using a temperature gauge to probe the depths of the lake in 1-foot increments is the key to good fishing. Now you search for the thermocline, where water temperature at different levels breaks sharply. Bass tend to school tightly in the thermocline because it provides them with more oxygen. Find its depth, then look for structure like rock piles, brush piles, trees, creek channel edges, ledges and so on, at the thermocline’s depth, and you’re in business. In winter, when bass go deep and are most sluggish, again the water temperature gauge is your key to success. Now you’re searching for deepwater areas in which the water is a few degrees warmer than other areas. Underwater springs, which often pump warm water into the cold depths of a reservoir, have huge schools of bass living around them in winter.
Optimum Temperatures: In his experiments under controlled conditions, Dr. Loren Hill found that bass rarely eat when the water temperature is below 45 degrees. Their feeding frequency increases between 47 and 70 degrees, but shuts off again at around 90 degrees. Dr. Hill’s magic temperature is 80 degrees. His studies show this is when the fish are most aggressive and active, and also when they grow the quickest. A bass’s metabolic rate – controlled by the water temperature – is the key. When the water’s cold, the fish’s metabolic rate is slowed. Therefore, it doesn’t digest foods as quickly as when temperatures are warmer. When a bass eats, but doesn’t digest its food, that means it won’t be hungry again for days. And since we catch most of our bass simply because they’re hungry, this affects our catch rates. Also, when metabolic rates are slower, the bass want something that’s easy to catch. That’s why slow-moving, bottom-crawling baits and lures work best at this time of year. Generally, as water temperatures increase in spring during the pre-spawn period form 45 degrees through 55 degrees, the bass will still be sluggish. They should be fished with slow-moving baits like jigs, spoons, worms and the like. When the water temperature increases from 60 degrees to 72 degrees, the fish enter the spawn mode. Then baits with a medium retrieve speed; top waters, crankbaits, spinnerbaits, jerkbaits, as wells as jigs, worms, and salamanders will produce best. During the post-spawn period, with water temperatures ranging from 72 through 90 degrees, it makes sense to fish fast-moving, reaction-type baits. Buzzbaits, top-water plugs, spinnerbaits, jerkbaits, jigging spoons and crankbaits make great additions to the plastic worm/jighead arsenal. For year-round success, try measuring your lake’s temperature. Use a device that permits temperature measurements into the depths of the lake, not just the surface. You’ll be able to accurately predict where the fish are, how aggressive they will be, and therefore the types of baits and lures that will produce more fish.
As the old saying goes, I’d rather be lucky than good. In this case, by knowing your lake’s water temperature, you’ll be well on your way to making your own good luck.

Water Temperature (F.) Lure Speed Best Lures
45 degrees very slow Small spoons, grubs, tubes, plastic worms, jigheads
50 degrees slow Grubs, mini jigs, plastic worms, jigging spoons, tubes, jigheads
55 degrees slow Same as above, plus spinnerbaits, small crankbaits,
slow working topwater baits
60 degrees medium Same as above, plus jerkbaits, medium crankbaits
65 degrees medium Topwater plugs, crankbaits, spinnerbaits, plastic worms, jerkbaits, salamanders, jigheads
70 degrees medium/fast Same as above, plus weedless spoons, buzzbaits,
topwater poppers
75 degrees fast Topwaters, buzzbaits, large crankbaits, weedless spoons, plastic worms, flutter spoons
80 degrees and above fast Same as above, plus night fishing baits