CD,
I apologize for the late reply. The last two weeks have been full of field work which has kept me away from the keyboard.
I can't recall any studies being conducted on Kansas crappie genetics since I've been around and my very quick search didn't turn up anything in the KDWP archives. I'll continue to look.
White crappie were native to most northeastern Kansas rivers. Over the years, stockings by government agencies and private landowners have produced the statewide population of white crappie that we have now. Black crappie are NOT native to Kansas, but self sustaining populations have been created through introductory stockings.
Black and white crappie, although quite similar, prefer and thrive in different water clarities. Black crappie do well in clear, deep, and weedy waters while white crappie excel in shallow, turbid waters. Since both species have been so widely introduced throughout the state they are available in most drainages and frequently co-exist. Young fish of both species are almost entirely planktivorous (feed exclusively on small animals called zooplankton). Adult black crappie can have a diet composed almost entirely of invertebrates where white crappie have usually switched to a fish based diet by the time they have reached 8-inches in length. Availability of gizzard shad enhances growth of both of the crappie species in Kansas.
Both species, especially the white crappie, are quite prolific. This can be beneficial in larger impoundments but can be detrimental in smaller waters. Over population, which leads to stunting, of the crappie is common where predation pressure or other population limiting factors is lacking. Too much natural recruitment produces high densities of small, slow growing individuals which are of little interest to anglers. Untimely crappie introductions in to newly renovated waters by well intentioned anglers can have disastrous effects upon the new sportfishery as the crappie are capable of out numbering and out competing predator species that are needed for crappie control.
Since crappie are prolific and capable of producing self sustaining populations in Kansas waters it is not necessary to supplementally stock crappie on a routine basis. Usually an introduction of a few adults or in some cases fingerling stockings is all that is required to start the crappie population. Crappie are not very selective when it comes to spawning substrates and their spawning requirements are met in the majority of Kansas waters making any stocking beyond the initial introduction unnecessary. Although most Kansas waters will support crappie, not all Kansas waters are capable of supporting crappie populations that are acceptable to anglers and therefore not all Kansas waters should be stocked with crappie. Presence of crappie in some impoundments will hinder the development of a quality sportfishery resulting in mediocre fishing at best.
Growth rates of Kansas crappie are more influenced by population characteristics (density, length frequency distribution, recruitment success, mortality, etc.) and impoundment productivity (availability of plankton, density of forage fish such as gizzard shad, etc.) than genetics. Theoretically, any crappie in Kansas that has ideal growing conditions and the time to grow should reach larger sizes. Poor crappie populations are not a result of poor genetics and excellent crappie populations are not a result of superior genetics. Many desirable factors must occur simultaneously to produce quality crappie fishing year after year. Even in the best Kansas crappie fisheries the population will cycle between high and low years as missed year classes move through the population. These missed year classes create 'holes' in the population and in time will effect the sizes of crappie that anglers find most desirable, causing an up and down cycle of quality fishing. If two or more consecutive years of bad production or poor growth occur, the 'hole' in the population becomes larger and the quality of the fishery decreases and takes longer to recover. The genetics haven't changed during the up years and the down years, but other factors that effect crappie regularly change and determine strength of year classes and growth rates of the fish.
I hope I have touched on the subject that you were interested in. I deviated widely from the thread title of Crappie Genetics to give some background on what does make or break our crappie populations.