We have made several posts in the past about F1 largemouth, urging landowners not to stock them because of the genetic issues that arise when they begin breeding with one another. Many landowners have taken this information to heart and stocked pure Floridas; more than a few of those ponds are well on their way to growing enormous largemouth. Some landowners that initially believed the science we presented to them, let themselves be swayed by the sales pitches of our competitors that will do anything to get a sale, and stocked F1s. They’ll have big bass quicker than the folks who stocked pure Floridas, because F1 and northern largemouth both grow faster until the fish gets to around a pound in size; at that point the Floridas begin outpacing both of the other varieties, and because Floridas also live longer on average than either a northern or F1, they ultimately get bigger. Those folks who bought the sales pitch and stocked F1s will see their ponds begin to decline after a few years, as the genetic problems worsen with Fx bass spawning with other Fx bass. That decline is what we’re trying to spare you when we urge you not to stock F1s.
This is really simple if you stop and think about it. We want to help you grow bigger fish, just as our competitors claim to want; anything we can do to make that happen, as long as it’s legal and ethical, we’re going to do. We used to stock F1s just like all of our competitors; we can buy them for the same prices that they buy them for, from the same hatcheries; we could breed them ourselves at our hatchery if we chose to, just as many hatcheries from Texas to South Carolina and everywhere in between do. The reason we stopped selling them is because we read a thread on a pond management forum in 2009 in which a prominent fisheries biologist was urging professional lake and pond managers in this country to think twice before stocking F1s because of the potential genetic issues with their offspring. We didn’t immediately stop stocking F1s after reading that thread – only after we began noticing a pattern among badly under-performing private ponds and lakes. What we noticed was that over and over again, the ponds and lakes that had the very smallest, most pitiful largemouth, worse by far than ponds and lakes that had never had any management at all, were the ones that had been stocked eight or more years prior with F1s.
We electrofished a 20-acre lake in west Tennessee that had great habitat, several acres of standing timber, along with a good depth profile; the largest largemouth we shocked up measured 10.5″. The lake had been stocked more than ten years earlier with F1s. We electrofished a 60-acre lake in east Tennessee that had been stocked with F1s as a new lake twelve years earlier; the biggest bass we shocked up in three hours of electrofishing weighed 1.25 pounds. We electrofished a 10-acre pond in central Alabama that had been stocked twelve years earlier with F1s – the biggest largemouth measured 11″. We electrofished a 22-acre lake in northern Georgia that had had F1s for several years – the biggest largemouth measured 10.5″. These are only a few examples; over and over again, we have worked on ponds and lakes where the bass were unusually small, only to find that every time, F1s had been stocked several years prior.
I have seen this phenomenon so many times that now it’s almost a reflex for me to ask the landowner, when the bass are running extra-small, what kind of bass he had stocked previously. If there are few to no bass larger than 11″, I can almost bet that the pond has had F1s for a while.
Understand this: even in a one-acre pond that has never had any management at all, and that has nothing more than plain old northern largemouth that have been in there for decades, it’s still common for there to be a couple or a few bass in the 14-17″ range, because even largemouth with poor conditions (insufficient forage base, poor water quality, etc.) can reach those sizes. That 16″ largemouth may be six years old; but it still has grown from year to year, even if at far less than an optimal rate, because it has normal genetics. Fx bass a few or several generations removed from the stocker F1s can be multiple generations into outbreeding depression; these fish are not going to get big regardless of what you do to the pond. Why is it that many government publications on pond management, when they mention hybrid bluegill, warn of the genetic inferiority of their offspring, yet not a single publication warns of this same phenomenon with F1 bass? Because hybrid bluegill are not big business like F1 bass and there aren’t powerful hatcheries lobbying/pressuring government agencies to not speak badly about their signature fish.
We regularly advise landowners who have northern largemouth in their ponds to stock pure Florida bass. Some F1s will be created; the major difference is, we’re not starting out with a cross, and the pure Floridas can breed with other pure Floridas, just as the pure northern bass can breed with pure northerns; whereas when a pond is stocked from the start with F1s the highest percentage of Florida alleles that any fish will have will be 50%. TWRA has been stocking pure Florida largemouth into Lake Chickamauga since 2001, and in 2015 a new state record of 15 pounds 3 ounces was caught from the lake; Chickamauga is now known as one of the premier trophy-bass public lakes in the country, and has dramatically bigger bass than it did prior to the Florida bass stocking program. A couple other points about that lake: TWRA stocks it annually with more Florida bass, hundreds of thousands of fingerlings every year, and a majority of bass in the lake now have Florida alleles.
One more data point on stocking Florida bass into waters that already had northern bass: one of the first lakes in the state that TWRA stocked Floridas into was a 40-acre lake about fifteen minutes from my house, Shellcracker Lake in Maury County. That lake has had Florida bass since 1998. To fully relate how successful that stocking has been, I have to tell you about another TWRA family-fishing lake that’s only about thirty miles from Shellcracker Lake as the crow flies; at 325 acres, Laurel Hill Lake is almost ten times as big as Shellcracker; it gets fished for largemouth as much as Shellcracker does. The biggest bass I have seen reports of coming from Laurel Hill in at least the last twenty years is eight pounds, and fish over six pounds are not common; conversely, Shellcracker Lake has produced several bass over ten pounds, including two bass over eleven pounds each that were recently electrofished by TWRA biologists; a tournament angler I know told me he lost a state-record bass in that lake. That’s the difference that Florida genes make.
It’s not even considered theory that the offspring of hybrid bluegill are inferior genetically, and that one of the most pronounced genetic problems with these fish is their extremely limited growth potential. Florida and northern largemouth were once considered two subspecies, but one of the leading biologists in largemouth research, David P. Philipp, has argued that they are two separate species; beyond that, outbreeding depression has been demonstrated even among two different groups of northern largemouth from different geographic regions. So if outbreeding can occur between two different cohorts of the same species, obviously it’s a major risk when you cross northern and Florida largemouth.
In sum, if you have a pond with northern largemouth and you’re wanting to catch bigger bass, you’re still better off stocking Floridas than staying with the northerns, particularly if you are diligent enough to periodically stock more Floridas rather than just letting the gene pool go to chance. If you have a new pond and you want big bass, why would you even consider stocking a fish that can ruin your pond ten years down the road when you can stock a fish that will breed true generation to generation?
Philipp, D. P., J. E. Claussen, T. W. Kassler, and J. M. Epifanio. 2002. Mixing stocks of largemouth bass reduces fitness through outbreeding depression. Pages 349-363 in Black bass: ecology, conservation, and management. American Fisheries Society, Symposium 31, Bethesda, Maryland.
Goldberg, Tony et. al. Increased Infectious Disease Susceptibility Resulting from Outbreeding Depression. Conservation Biology 19(2):455-462.