Author ~ Dan Ashe
First let’s start with the basics. Nearly everyone has seen largemouth bass in an area that has been swept clean near the shoreline during the spring. These swept areas are bass nests or beds. Spawning takes place when the water temperature reaches 60-75o F. The male constructs the bed and courts a female to spawn, where he then releases his sperm to fertilize the eggs. Fertilized largemouth bass eggs are yellow to orange in color. The male stands guard over the eggs to protect them from predation and continually fans the water to keep water moving over the eggs to keep silt from building up on top of them, while the female leaves once spawning is complete. Largemouth bass sexual maturity is influenced by size more than age, with most bass reaching sexual maturity with the ability to spawn at around ten inches. The largemouth bass in our lakes usually attain this size at about age two. Largemouth bass beds have been reported to contain anywhere from 5,000 to 45,000 eggs with the differences in number dependent on the size and condition of the spawned female. The time it takes largemouth bass eggs to hatch is highly influenced by water temperature with hatch time at 65o F being about 2 ½ days.
Life for young largemouth bass is hard with very few surviving their first year. One paper I have found cited that only two tenths of one percent of young bass made it past their first year in an Alabama lake. There are several factors that are considered important in determining survival, most notably time of spawning, temperature, predation, and available forage and habitat.
Generally speaking, larger bass spawn earlier than smaller bass. This characteristic is important to young bass survival. Fish that hatch sooner have longer to feed and grow before winter sets in and thus a greater chance of over winter survival. There is some debate as to whether bass populations with a large number of big fish have a distinct advantage to maintain a more constant and stable population in terms of steady recruitment. The down side of having an earlier spawning time is that these fish are more vulnerable to extreme temperature fluctuations than those that are spawned later when the likelihood of a spring freeze is less likely. Therefore, the debate goes on. I guess it all depends on what year you want to look at.
Temperature plays the most significant role in early survival of bass, where it can influence entire year classes of bass. As stated earlier temperature determines how long it takes for eggs to hatch, the longer it takes eggs to hatch the likelihood of predation of those eggs increases. In addition, once bass hatch they are not mobile, they are still on the bottom of the bed feeding off a yolk sac. Again, the longer a fish is immobile the chances of predation increases significantly. Water temperature determines how long it takes for the bass larvae to develop and become mobile. At 70o F bass are able to swim in about 10 days after hatch, at colder temperatures this time is significantly longer.
Once the bass fry become free swimming they must begin to feed within days or they will die. Bass fry initially feed on zooplankton (microscopic animals) and the amount of zooplankton is dependant on phytoplankton (microscopic plants). Lakes that are turbid, acidic, etc., generally are not productive in terms of plankton production, with low fish recruitment due to inadequate forage for young fish. Bass fry are voracious feeders needing to feed several times a day. Food passes through their stomachs every few hours. Over time as the bass grow they will shift to a fish diet. It is imperative that ample forage fish be available for both the larger and younger bass. Bass will always eat one another, but if there are other prey species available the amount of cannibalism will be less.
A-Jay
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