(Feb. 19, 2013 - Athens, TX)...
Given recent events I thought it would be a good idea to reiterate why the ShareLunker and Operation World Record programs are operated in their current fashion, specifically, why hybrid ShareLunkers are not included in hatchery spawning events.
We should start by noting that hybrids are included in ShareLunker spawning events when non-introgressed Florida largemouth bass ShareLunkers are not available. This has been done in the past and will continue in the future. No one is of the opinion that hybrid largemouth bass cannot reach a large size, even a state or world record size. Nor does anyone think there isn’t something special about the genotype of a hybrid largemouth bass that reaches a trophy size. However, one purpose of the ShareLunker and Operation World Record programs is to produce offspring that will reach large size. The use of non-introgressed Florida largemouth bass in the breeding programs enhances this probability.
The reasons for this are both theoretical and tangible. Size, not just in largemouth bass but in humans, mice, and everything else, is a quantitative trait that results from interactions between the genotype and the environment. The phenotype of size is the result of actions and interactions at and among hundreds to thousands of loci, each accounting for a fraction of a percent of the overall variance. The genetic contribution to this variance can be partitioned into three types?additive, dominance, and epistatic. While both a hybrid largemouth bass and a Florida largemouth bass will pass on the additive genetic components (or a portion of them) to their offspring, the epistatic and dominance configurations (or similar configurations) are more likely to be realized in the offspring of a non-hybrid cross.
The tangible evidence can be seen in our reservoirs. If you could roll all of our reservoirs into one big water body to create a "typical " Texas reservoir, 5 percent of the fish would be Florida largemouth bass and 90 percent of the fish would be hybrids. However, among all ShareLunker entries, 50 percent of these fish are Florida largemouth and 50 percent are hybrids. That means that 5 percent of the population (Florida largemouth bass) is responsible for 50 percent of the ShareLunkers, and 90% of the population (hybrids) is responsible for the other 50 percent. Given two fish, one a Florida largemouth bass and one a hybrid, the Florida largemouth bass is about 10 times more likely to reach a size of 13 pounds or greater.
Spawning a hybrid donated to the ShareLunker program and stocking out its offspring does not, by itself, hurt anything. However, TPWD has limited staff, time, spawning capacity, and pond rearing space for dealing with "special " fish, and those resources are best used by incorporating non-introgressed ShareLunkers into the spawning program. This increases the frequency of non-introgressed Florida largemouth bass in the population as well as the probability of producing offspring that will themselves reach trophy size. There will always be plenty of hybrids even if we never cross them.