I’ve been doing some research on fishing Okeechobee and read an article that says the ideal ph level for bass in that lake is between 7.4 and 7.9. In all my years of fishing, I’ve never considered ph level to be a factor much less the magic formula for finding bass but the more research I do on the subject, the more and more it makes sense especially after reading this article in Bass West Magazine by Keith Jones:
It’s bad enough keeping track of all the things we see, much less the things we can’t. Yet, in bass fishing, sometimes the invisible is more important than the visible. Included in the former is chemistry, which, at times, can have profound effects on bass health, location, and hence your fishing success. Topping the list of important water parameters is pH.
Technically, pH is the negative log molar concentration of hydronium ions in water. In more down-to-earth terms, pH is a measure of water’s acidity or basicity. It is measured on a scale 1-14 with the middle ground, pH 7, considered neutral; pHs less than 7 are acidic, those greater than 7 are basic. The greater the numerical distance from neutrality, the more acidic or basic is the water. A pH of 1 is extremely acidic; 14 is extremely basic.
Unfortunately, the simplicity of the pH scale is somewhat misleading. Most folks tend to think that each unit change in pH is equal. If this were so, then a 2- unit change in pH would equal twice the amount of acid/base difference as that of a 1-unit change. Thus, it would take twice as much acid to drop from pH 7 to 5 as that needed to drop from pH 7 to 6.
However, pH is actually an exponential scale. Every unit change in pH equals a 10-fold increase or decrease in acidity (or basicity). Thus, dropping from pH 7 to 6 is a 10-fold increase in acidity. However, dropping further to pH 5 is another 10-fold increase, or a 100-fold increase (10 x 10 = 100) in acidity from pH 7. For this reason, even minor deviations in pH around the more extreme values constitute much greater changes in acidity (or basicity) than seemingly major changes around the neutral mark. For example, merely dropping from pH 3.1 to 3.0 equals an increase in acidity more than 238 times greater than dropping from pH 7 to 6.
Natural waters vary tremendously in pH, ranging from about 3.2 in peat bogs to greater than 10 in some alkaline desert pools. They also vary considerably in their susceptibility to pH changes due in part to how much buffering capacity the water carries in the form of inorganic salts. These salts rapidly absorb any excess acids and bases, preventing the pH from falling or rising. “Hard water”, which carries a heavy salt load, keeps a relatively constant pH. In contrast, “soft water” carries little salt, has little buffering capacity, and changes pH easily.
Bass cannot live throughout the entire natural pH range but have been found in a remarkably diverse spread of acid/alkaline habitats. Healthy populations of Florida bass have been found as low as pH 4.3 in some acidic lakes. I have no information about the upper pH limits of bass, but I suspect it lies somewhere in the range of 8.7 to 9.2.
Bass can tolerate such a wide pH range largely because of their ability to regulate their internal pH. Unlike a bass’ body temperature that cannot be regulated physiologically but depends strictly on the ambient temperature, internal pH can be maintained at a constant level over an appreciable range of environmental pH. Bass accomplish this by continually adjusting the relative alkalinity (the ratio between acids and bases) of their blood and tissue fluids. Adjustments are made by expelling excess acids and selective ions in the urine and by controlling the rate of breathing (increasing the ventilation rate removes excess carbon dioxide from the blood, thereby raising blood pH.)
But bass have their limits. Regulating internal pH is energetically costly, and there is only so much physiological capacity available for tolerating hostile pHs. If it stays too long in a highly basic or acidic environment a bass will eventually lose control of its internal chemistry. Bass suffering from sublethal pH stress will suspend many of their normal activities, including feeding. Prolonged exposure to lethal pH levels will ultimately result in death.
Obviously, then, it makes sense for bass to stay at pH levels they can physiologically handle. In other words, if they want to avoid stress and possible death, bass need to behaviorally regulate their pH exposure much like they do with temperature. Recent research has shown that bass acclimated to pH 7 avoid contact with acidic water in favor of moderately basic water. It is not known if bass avoid highly basic water, but it seems reasonable to assume that they would at some point.
If natural waters maintained a uniform pH over space and time, then bass pH preferences would be irrelevant. Some waters might be acidic, others basic, and still others neutral. But if they all stayed uniform, then the only issue would be whether bass could tolerate that pH present in any particular body of water. The bass would have no available choices from which to choose.
However, natural waters are rarely, if ever, uniform in pH. Decaying plants frequently produce acidic compounds that drive down the pH of overlying waters. Thus, bottom waters generally run lower in pH than surface waters. On the other hand, photosynthesis by algae, aquatic plants, and phytoplankton will drive the local pH up. Chemical pollutants can raise or lower pH depending on the specific nature of the pollutant. Some soils are acidic. Others are basic. Soil run-offs, therefore, can significantly alter the pH of feeder creeks and those areas where they empty into the main lake or stream. Agricultural fertilizers and nutrients are typically basic. Run-offs from farmlands will often raise the pH of recipient waters.
Variances in pH can reach dramatic proportions in the spring due to higher than average rainfalls and snowmelt. Normal rain has a pH around 5.6. Heavy rainfalls can lower surface pH and those areas that receive substantial run-offs. In geographical areas downwind of highly industrialized sectors, fossil fuel exhausts have been known to acidify rain to pH levels of 2.5 and lower. If, instead of rain, the acid is stored in snow, the snowpack essentially serves as a giant acid reservoir. During spring melts, the acid is suddenly released in heavy doses, sometimes with devastating effects.
Given that bass monitor their external pH carefully, it seems bass anglers would be wise to likewise keep tabs on this critical water chemistry parameter. If it matters to the bass, then it should also matter to the bass angler.
At this point you might expect me to heartily recommend your buying a pH meter. Well, not heartily, but maybe I would as long as I can throw in a few words of caution.
Laboratory grade pH meters tend to be spendy items, ranging anywhere from a few hundred to well over a thousand dollars. And, because of their high sensitivity, good pH meters require constant recalibration with standardized buffer solutions to ensure accurate readings. The better ones also come with a temperature knob to allow for temperature compensation. Due to their fragile nature, laboratory grade meters are not well-suited for rough-riding bass boats.
More rugged, but usually less sensitive hand-held units are becoming more popular among those professionals who annually take a lot of field measurements. This includes fish farmers, university labs, and government regulatory agencies. These units lie more in the price range anglers can afford, and there is usually a good selection from which to choose. Any good aquacultural supply house should have them listed. Our own lab has had fairly good luck with Aquatic Ecosystems out of Apopka, Florida (www.aquat-iceco.com), but others can be found on the Internet.
If and when you choose to buy a meter, I strongly suggest getting a model that can be periodically recalibrated with known buffer standards (usually sold separately). In any case, do yourself a favor. Don’t even consider buying a $29.95 Mart special that has no means of regular adjustment and uses a pH probe that looks like it came straight from the Disney Store. Without any means of standardizing the meter you are obliged to take the manufacturer’s word that your new electronic device reads correctly. And, quite frankly, I wouldn’t. Usually, pH meters come with a pretty short cable, about 18-24 inches in most cases. If you can, get a cable long enough to measure pH over a range of depth. Something like a 20-ft cord would be great. That way you get a much more accurate pH profile from the surface on down. Measuring only the surface pH is next to useless. You might as well just ignore the invisible altogether.
After reading this article, I figured a ph meter would help my fishing but they’re not cheap… like $1,000. There goes that idea. It might be worth it if I had money to burn. After all, it’s all about finding the fish and if this ph thing actually works, it’s definitely worth the money. Heck, most electronics for fishing costs more than that anyway. I’d sure like to talk to someone who’s used it.
Then I ran across this article by John Weiss in his book entitled Advanced Bass Fishing which suggests that oxygen levels have just a profound an effect on bass as ph.
It was in 1974 that an Austin, Texas scientist by the name of Dr. Martin Venneman, who also happened to be a devoted fisherman, decided to analyze the watery world of bass. Using sophisticated lab equipment on loan from Texas A & M University, Venneman studied numerous bodies of water and made a startling discovery. “At any given time,” Venneman reported, “from 50 to 80 percent of the water in any lake does not contain enough oxygen to support fish life.”
The explosion you heard was a revolution in bass fishing that has rippled from border to border and coast to coast as anglers nowadays use modern science to unlock many of bassdom’s previously guarded secrets. And many innovative companies are helping them by providing scaled-down, economical devices that are enabling them to enjoy far more fish-catching success than ever.
It’s important to emphasize that oxygen-monitoring equipment and pH meters (to be discussed shortly) will not guarantee that you will consistently be able to find or catch bass. What they do guarantee is that you will not waste time fishing where no fish can possibly survive. In other words, oxygen and pH evaluation are two easy-to-learn techniques the seasoned angler can use to systematically eliminate barren or unproductive water. All efforts may then be concentrated in those areas almost certain to contain large numbers of fish.
It should also be mentioned that bass living in rivers and streams are seldom influenced by changing oxygen or pH levels. The ever-present current in such flowing waters generally makes any unfavorable changes in the water chemistry so short-lived that they have no effect upon the bass and do not force them to radically alter their habits or move to other areas.
Oxygen and pH evaluation is most useful to anglers on larger lakes and reservoirs where miles of shoreline twist and turn to form numerous channels, bays, coves and other such places which may be subject to wide variations in water temperature, light penetration and, most important, oxygen and pH levels.
They Gotta Breathe!
All species of fish must have enough dissolved oxygen in the water around them in order to live. Although bass are quite tolerant with regard to other environmental variables, their requirement for minimum oxygen levels is absolute. There can be no compromise or adaptation. If oxygen levels are too high, or too low, they must either move out of the area altogether, or perish!
Survivable oxygen levels for bass range from 5 to 13 parts per million (ppm), though they highly prefer and will seek out waters with 9 to 12 ppm oxygen. If the oxygen level falls below 3 ppm, the fish will die of asphyxiation. And if they remain in areas with more than 13 ppm, they will experience oxygen poisoning.
The effects of oxygen depletion or oversaturation are most likely to be noticed in the late summer and fall months, and though they may last only a day or two, they also may last several weeks. This is why anglers should frequently take oxygen level readings in those lake sections they fish most regularly, especially if they are having difficulty finding and catching bass.
Most oxygen meters available today are small, battery-operated, hand-held devices that cost less than $50 and are available through mail-order houses such as Bass Pro Shops and Cabela’s. They have an oxygen-sensing probe attached to a metered line that is lowered into the water to various depths. When a button is pushed, a needle gauge registers the parts per million of oxygen in that area.
To reap the greatest benefit from an oxygen monitor, you should spend a little time, at the very beginning of the first day on the water, determining oxygen levels in various portions of the lake or reservoir. Motor back and forth across the lake, taking oxygen readings here and there and jotting down the numbers on your contour map. Now you’re ready to begin fishing the types of depths, bottom structure and cover which bass in that area are likely to be using at that particular time of year. You’ve completely eliminated from consideration those areas found to be incapable of supporting fish life, regardless of how “bassy” they may look.
On subsequent days on the water, you need only quickly reconfirm the oxygen levels at your favorite fishing locations. If something has happened to radically change the oxygen level (most often an abrupt change in wind direction or barometric pressure), you can be pretty sure that the bass have left the area, and so should you.
Try a pH Monitor
The pH of a solution is a measure of its acidity or alkalinity. The pH scale runs from 0 to 14, with a measurement of 7 considered neutral; anything lower than 7 is acidic and anything higher than 7 is alkaline, or basic.
Like all animals, fish must maintain a certain chemical balance in their blood and body fluids if they are to survive. Since the pH of their blood is slightly alkaline (7.6), it is not surprising that bass seek out water with approximately the same pH. When the water pH is near this value, bass are best able to withstand stress and utilize the oxygen in the water properly. This is not to say bass will travel far distances to find an ideal pH; the species are very adaptable and can survive in water with a pH ranging from 6.7 to 9.6. However, given any choice, if there is water within their immediate region that has a pH of 7.5 to 7.9, that is where bass will be.
It was in 1979 that Dr. Loren Hill, then chairman of the Zoology Department at the University of Oklahoma, developed the first pH meter for fishermen. Other companies have since introduced their own devices, which operate in basically the same manner as oxygen meters and are comparably priced.
Most advanced anglers use an oxygen meter first, to locate themselves in a specific lake region where bass have concentrated. However, since the depth range in a given area may be from 1 foot (at the shoreline) to 100 feet deep or more far offshore, the angler still is faced with an enormous amount of water to explore. A pH meter dramatically reduces this time if it is used to determine a so-called pH profile.
This procedure entails lowering the pH meter’s probe into the water, taking a reading at the surface and then subsequent readings at one-foot intervals all the way to the bottom. After recording these values on a notepad, you’ll discover a pH breakline at some particular depth—that is, a point where the pH changes rapidly.
For example, readings may fluctuate back and forth by one-tenth of a unit, and then suddenly, at some specific depth, you’ll note a full one-unit change in pH. This swing may not seem significant, but in actuality it is. The pH scale is logarithmic, so pH 8 is ten times more alkaline than pH 7, and pH 9 is 100 times more alkaline than pH 7.
The value of understanding this is that Dr. Hill learned that in any lake the pH breakline is the depth at which a majority of bass congregate and are the most active.
What a boon to anglers! With an oxygen meter, any fisherman can easily and quickly learn what regions of the lake are holding the greatest numbers of bass. And, in refining his search, his pH meter will tell him the depth the fish are at. Now all he has to do is look for an abrupt change in bottom contour at that depth, or cover bass like such as weeds or stumps at that depth, and begin catching fish.
Some may disdain the use of the new bass science, claiming it eliminates the romanticism and mystery of randomly chancing upon a fish here and a fish here. But personally, rather than spend most of my day “fishing,” I’d rather spend it “catching.”
Maybe I’ll go for a oxygen meter for $50 which seems a lot more reasonable than $1,000 for a ph meter. If anyone out there has experience with an oxygen or ph meter, please leave a comment and let me know your thoughts on whether or not it’s worth the money.
