My reference to the past discussion of
http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=20;t=001403 from the topic of: 4" bass (Types of Fish to Chose; Mar 22 2005) evidently did not fully answer your question.
Let me discusss this a little more and see if this info satisfies your needs. I am not a southern bass expert but I know enough about LMbass biology that I can make a good educated guess for you and explain it further.
BACKGROUND - Bass growth rate, as with most fish, is largely dependent on the amount of food they are able to eat. Other factors also affect the growth rate. We could in theory keep a bass in the short size range of 2"-4" for several years by limiting its food intake to just a maintinence diet. We give it just enough food to keep it alive but not enough to allow for much growth or body fat. At the other extreme, if we fed a relatively normal bass as much food as it could eat on a regular basis this fish could grow to 10" to 12" the first year if temperatures most all year were in a warm range(65F-80F); preferred 72F-82F. The second year with the same conditions this fish could be 16"-18" long; depending.
YOUR case. I am assuming you currently have these 4" and 7-8" bass in your pond in LA. If you drained the pond you may also find a couple or a few 9"or10" long bass that are about the same age as your 7"-8" bass. . They are all very likely last year's 2004 hatch of fish. However they may be from the same or differnt spawns in 2004; such as early spawn (April - May) 7"-8" vs a later hatch in June to August (4"-5" bass). Real late LMbass spawns are not common but they do happen esp in southern areas for various reasons.
As an alternative your 4" bass and 7"-8" bass could even be from the SAME spawn or nest. Not all fish from the same hatch grow at the same rate. In LM or SMbass, females usualy grow slightly faster and reach ultimate larger sizes than the male bass. The 4" bass could be the runts of the spawn and the 7"-8" bass could be the more aggressive, genetically superior and or better adapted at predation of other smaller fishes, thus they grow faster than their 4"-6" siblings. Smallest bass that you are seeing could be thriving on a diet more of bugs and small invertebrates compared to the next larger size group that are eating more fish. Often the smallest siblings eventually become one of the larger bass' dinner. However a fair number of the slower growers often but not always get eliminated from the gene pool by predation from the larger more aggressive fish. A few runts or slower growers always manage to survive.
There are a lot of variables to fish size and growth similar to humans. It is not all black & white and explained with simple answers. In humans of a city there are short people (3'to 5') and the tallest basketball player types 6'6"-7'); many at the same or similar age. All sizes and shapes and actual birth dates in each year group or year class. People grow differently than fish but I think you get the picture.
If these 4"-8" bass are newly stocked bass then obviously growth rates are variable for these initial stocked fish. If these fish were produced naturally in your pond by parent fish then you are probably dealing with two different spawns from 2004. As of today's date of March 30 the 4" bass that you are catching in your pond cannot be young fish from the 2005 hatch.
Skilled fishery biologists can pretty accurately estimate the age of these fish by technical laboratory methods. I will not elaborate on them here because these are not feasable or practical techniques for the general pond owner. Special equipment is required.
Did this finally answer your question and Did it stimulate another question relating to your small bass?
