As promised in the last issue, we’ve got more on the subject of the “80ºF zone”, and once we re-read that dog-eared pamphlet, we noticed that according to our logbooks, which we must admit we have to our own detriment not kept up as meticulously as we did in past years, the water temperature penciled in against the catches that we have entered , were mostly in that magical 80ºF zone – or at least very close to it.
But it bears repeating that just on one hundred percent of those catches were made in areas that not only had water around the 80-degree mark, but also offered all the conventional structures or cover that bass relate to. The point here is that no matter what the temperature, a bass will not easily give up its deep-rooted instinct to relate to structure and cover, and the reason is simply because that is where they find their food.
The key, we therefore suppose (logically) is that one needs to discover where these three variables are found together, namely temperature, structure and/or cover. It is also no surprise that the water depth at these spots was never less than a foot and never deeper than 15 feet.
Another fact that emerged from the research that was carried out – and it serves only to underline that a lot of the research that is carried out throws up information that confuses the issue – was that while the bass preferred to hang out in the 80-degree zones, most of their feeding was made in water that was slightly cooler, namely between 75 to 78 degrees.
This concurs with findings made public by Doug Hannon, the well known “Bass Professor”. “Largemouths feed most actively in water of about 76º,” he says. “At that temperature the fish is at its liveliest, even though if it has a choice it will seek somewhat warmer water in the 78 to 80 range.”
Hannon likens this behaviour to that of humans, pointing out that while we humans prefer the comfortable weather of summer, we tend to be more active when the weather is cooler.
The research in question using radio tracking equipment clearly showed the bass’ preference for warmer water - bass were seen following the 80 curve in both daily and seasonal patterns.
So all this is quite interesting, maybe fascinating, but it begs the question: where in South Africa do we find bass lakes that have warm discharges from power stations?
Hannon provides some solutions, pointing out that all dams have natural thermal build-ups, and the key is “merely” to locate these areas to find bass when the overall water temperature is below the preferred zone.
One of the most important keys to finding such warmer areas is the position of the sun, Hannon points out. In winter, for example, the southwest corner (we’re talking south of the Equator here, remember – in America it would be the northwest area) and sometimes the entire southern shoreline can provide a warm water holding area. Bass will also often move into areas with dark mud or grass bottoms where the sun’s heat is more easily absorbed and the water warms up more rapidly than it would be over a light, sandy bottom.
And in summer bass can also suspend in the thin, warm layer of water that forms on the surface during calm, sunshine days, he explains. “In this situation the fish may be holding over 25 feet of water but they are all in the upper foot of water. In this scenario they can be tempted by a surface lure but obviously a bottom fished worm or jig will not even be noticed.”
Other areas where bass tend to congregate when the water temperature in most of the dam is below the preferred range include the rip-rap at dam walls, particularly when these face north and receive direct sunlight for most of the day. Rock faces facing north are also well known places where the water warms quicker, and in some dams where old, tarred roads are submerged the same phenomenon will be found. All such places are heat traps where the water can be as much as ten degrees warmer than in the open stretches of a dam.
Wind also plays a part in this eighty degree saga. When the wind blows steadily for an extended time across a dam’s surface on a bright, hot summer’s day, the warm surface water is gradually pushed towards the windward shoreline and a thicker layer of warm water develops as the surface water mixes with the deeper water.
Such areas demand good boat control but will more often than not hold more bass than the calm but cooler waters on the leeward side. So it could be a good call, particularly for well equipped competitive bass anglers, to persist in the rougher windward shore area, although in extremely hot weather, there is the converse situation where the shore side water is too hot and fishing is better on the calm, leeward side.
Keeping things warm needs some insulation, and areas that have coverings of lily pads, grass and weed beds, even water hyacinth will retain the heat at a more even temperature than open water areas.
Conversely, such areas also can act as cooler refuges in particularly hot weather, with the water several degrees cooler in the shade than open water of the same depth.
With water temperature playing such a major role in locating bass, it is obvious that if you don’t have any temperature reading equipment on board it’s quite likely that you are not catching as well as you should be. The basic equipment is the temperature gauge supplied with your electronics, although this will only provide readings taken on or just below the surface. A hand-held thermometer that can be dropped into the entire water column is an essential addition to your bass locating equipment (remember our experience with the guide as noted in the previous issue?). It needs to be kept at a specific depth for at least a minute to get an accurate reading, and it can be laborious, but when we seek bass the time and effort spent will be well worth the effort!
Scientists are agreed that in 80-degree water a bass’ metabolism is at its highest and it needs to feed regularly, but because the amount of oxygen it needs to survive increases with rising water temperatures, the fish display less energy than in slightly cooler water. Above the 80-degree mark bass become lethargic and the metabolism drops off dramatically, so then you have to seek out cooler water.
We must state also that while more recent studies have proved that bass can survive in water much higher than 80-degrees, their feeding urge decreases drastically.