I live in Colorado and our bass season runs March through October. Like many animals reproduction is the most important element in the life of a bass and it plays a significant role in bass behavior and how we fish for them.
I like to break down the season as pre-spawn, spawn and post spawn. Keep in mind that all of the bass in a given fisheries do not spawn at the same time. Spawning usually takes place in the spring over a period of around six weeks, but it can vary.
There are many environmental factors that affect bass behavior but by far the most significant is the water temperature. Bass can tolerate a wide range of water temperatures from the 30’s to the low 90’s but fly fishers are most successful when the water is around 50 degrees through mid 70’s. I start fishing at ice out when the water might be 40 degrees and scratch out fish but as the water warms the bite improves.
Pre-Spawn Period: Mar-June
As the water warms in March and April a bass’s metabolism increases. They instinctively know that the rigors of spawning are coming up and they feed voraciously.
Along with heavy feeding the hormones are starting to flow which adds fuel to their aggressive behavior. This is the best time of the year to catch large numbers of bass, and the best chance for large bass. A good bite can occur throughout the day and go ballistic when the barometric pressure drops. When a windy front rolls in, especially if accompanied by rain or snow I catch more big bass than at any other time. When a blue bird high follows, the bite can significantly decrease until the barometer steadies, when a good bite will resume. Much of the prime spawning habitat is near shore and many bass will be cruising the perimeter checking out potential spawning areas. I will focus on the shoreline but any area where a bass might spawn, like a flat or reef can be productive. My technique is simple. I use a Sage One 6 wt rod, cold water WF 6 Clouser taper floating line, 9 foot leader with an OX FluoroFlex Plus tippet and a Meat Whistle. Any color Whistle will work but my confidence colors are olive or virile when the weather is nice, and black when it is windy and raining or snowing. I employ the passive streamer technique the majority of the time.
Spawn: May- July
The magic temperature for bass to begin spawning is around 60 degrees but that can vary. Males create and defend the spawning beds against all intruders. When the time is right females will come to a bed and lay eggs and the male will fertilize them. A female will lay eggs on many beds, insuring a healthy genetic diversity. The male will defend the newly hatched fry with his life until they are able to swim away on their own. After the spawn has ended and the young bass have left the bed, the adult bass will go on to eat as many of the fry as they can.
Another chapter in the mysteries of nature. During the spawn I don’t intentionally fish the beds, but when blind fishing, running a Whistle through an occasional bed is unavoidable. Usually the aggressive males are caught and they will return to the bed upon release. Remember that all the bass don’t spawn at the same time, and during the “spawn” there will be pre spawn and post spawn bass. As the water is warming, sometime in May the top water bite will begin and I start to carry two rods. One rigged with a Whistle for subsurface, and another rigged for top water.
My favorite rod for top water is a 4-wt Sage TXL-F with a WF 4 cold water Clouser Taper. I use a 71/2 foot OX leader with a regular mono tippet. Fluoro can tend to sink a popper. I like to keep it simple and most often use my popper pattern, The Cat for top water. I usually have a Spork as a dropper off the popper. Fishing the popper-dropper combo is fun, catches more fish than the straight popper, and the Spork is not only a good bass pattern but a killer brim fly.
Post Spawn: June-Oct
After the bass have spawned the fishing becomes more unpredictable. The fish disperse throughout the lake and can be difficult to locate. Some of the large bass can become nocturnal. They can at times feed aggressively but not consistently like earlier in the year and the best bite is usually early and late in the day.
I still fish subsurface, most often when a cold front is coming through, but this is the time of year when my focus is top water. The most productive top water fishing is when it is calm with no sun on the water. When the water starts to cool in the fall the bite can go wide open, just like when the water starts to warm in the spring. Bass instinctively know they need to fatten up for the winter, just like a bear. The fall bite is not as predictable as the spring bite, but a times can rival it.