As a producer of F1 hybrid largemouth bass, I found the presentation by Dr. Wes Neal to be of particular interest.
With the assumption that Dr. Neal is correct with his recommendations, we should be stocking EITHER pure strain northern LMB OR pure strain florida LMB in our ponds instead of mixing them up or stocking F1s.
Conclusion: Most of us, including me, have been screwing up big-time. How do we swallow this? How do we manage from now on in lieu of this new evidence? How do we sleep at night?
I read somewhere that it's believed that the current world record LMB may have been a naturally-occurring northern-Florida cross. And, I know that tiger bass grow exceedingly fast in the South, as evidenced by multiple posters on here stating they've had them grow three pounds per year; and obviously they hit lures much better than Floridas. So I can't see how tiger bass could be wrong all the time.
But I realize also that I may be off as to what the presentation was about, though I'm guessing it pertained to either F1 offspring being genetically inferior, or naturally-occurring Florida-northern crosses being inferior, or the offpsring of naturally-occurring Florida-northern crosses being inferior, or all of the above...Which I suppose translates to, I wish I had been there and heard the presentation! Details for those of us poor slobs who missed it?
To quote one Southern PM at the Conference, there is a wide band of intergrades (Fx's) in FL/GA/AL that have been there for 10,000 years and (in all likelihood) produced the standing world record. Where's the outbreeding depression there?
"Live like you'll die tomorrow, but manage your grass like you'll live forever." -S. M. Stirling
Great thread topic...I'm curious to hear more. Count me as one of the poor slobs who missed the conference.
"Only after sorrow's hand has bowed your head will life become truly real to you; then you will acquire the noble spirituality which intensifies the reality of life. I go to an all-powerful God. Beyond that I have no knowledge--no fear--only faith."
Todd I intend to purse this with Wes Neal. Did not want to do so in public at PB III as it would seem rude. We have been over this here. At this time I do not agree with his premise. See Theo's comment.
IMHO where outbreeding depression exists, it should affect some but not all of whatever Fx's are present due to the random recombination of genes from both parent strains. Affected individuals should tend to be eliminated in competitive situations.
I think any fish population where millions of eggs are thrown into competition yielding tens of adult survivors is extremely competitive. So maybe the outbreeding depression occurs in F1 bass offspring, but is extremely hard to ever observe.
"Live like you'll die tomorrow, but manage your grass like you'll live forever." -S. M. Stirling
Dang it I hoped to get to work and not have to post right now but could not let this one go by without a comment. I did get to clear our intake pipe again 2’ under sediment from raging creek and no water getting to fish.
Todd I was listening closely as well. However I’m posting to calm you down. I do not think we have been screwing up. If you noticed once he was done I went over to talk with him before he left. This was not new information but it hit home. My main question to him was this....What is difference in growth of plain old inbreeding amongst pure genetic bass from one source and outbreeding depression? Short answer not sure the difference (hard to research this) and doubts any significant diff in growth. Add in Theo's thoughts and makes it even less important. He did say many times age and food more important. He is doing some research in Puerto Rico and we might have a few more answers in a few years. I got his contact info and I will ask him to chime in here if he has a moment. Question is what should we as fish stockers and consultants be doing? So did I screwup adding F1 bass all these years? I do not think so. If I added Fx from unknown source then they will still be inbreeding. If I added pure northern bass then they would top out at 8 lbs. If I added pure Florida hard to catch in a few years. Adding F1 gives best of both the worlds to original fish. So if a 5% reduction in growth in future generations still think it is best to put them in, don’t you, other thoughts? The take home I got from this talk was good news for you and I Todd. That is to help combat inbreeding we need to add a few adult bass to some ponds that are older. Fred Bingham said his is 60 years old and never added any. Also if possible think it a good idea to get some bass from a couple of sources if possible. Mixing up the genetics as I mentioned in my talk is also good idea I feel. Also might start a trade program where I get bass from one pond and trade with another, oops wait a min then we could transfer a disease what is a consultant to do.
Thanks to you all for the replies. Appears as if my skepticism is shared amongst other forum members. Here is a copy of recent correspondence between Dr. Neal and I:
Quote:
Dr. Neal,
I am glad to have seen your presentation at the PB conference. As a recognized producer of the now infamous F1 largemouth I am somewhat concerned about the implications of outbreeding depression.
I have a few questions for you. If you have the time to respond that would be very much appreciated.
About how many years or generations does it take for significant depression to occur with F1s?
How does the mixing of pure strains (50F:50N or 70F:30N or 33F:33N:33F1s) as lmb are stocked initially influence genetic depression down the road?
How do you recommend that growers in my position deal with ponds/lakes that have already been stocked with F1s only or mixed pure strains in the future?
Pure northern lmb are available almost year-round due to the fact that they are easily feed-trained. This makes larger fingerlings available for good survival rates. However, as you probably know, pure florida bass are difficult to feed-train and so they are only available in May-July time frame at a small size. Given this practical consideration, what is your recommendation for stocking existing lmb ponds with more bass fingerlings for genetic enhancement/inbreeding relief?
Thanks again for your presentation. For me this information may have more impact on the industry than any other presentation at the conference.
Then his reply:
Quote:
Todd:
I have modified the following description of outbreeding depression from the Wikipedia description:
“Outbreeding depression refers to cases when offspring from crosses between individuals from different populations have lower fitness than progeny from crosses between individuals from the same population. This phenomenon can occur in two ways. First, selection in one population might produce a large body size, whereas in another population small body size might be more advantageous. Gene flow between these populations may lead to individuals with intermediate body sizes, which may not be adaptive in either population.
A second way outbreeding depression can occur is by the breakdown of biochemical or physiological compatibilities between genes in the different populations. Within local, isolated populations, alleles are selected for their positive, overall effects on the local genetic background. Due to non-additive gene action, the same genes may have rather different average effects in different genetic backgrounds--hence, the potential evolution of locally co-adapted gene complexes. In other words, individuals from Population A will tend to have genes selected for the quality of combining well with gene combinations common in Population A. However, genes found in Population A will not have been selected for the quality of crossing well with genes common in Population B.
However, it is critical to understand that reduced inbreeding depression in first generation hybrids can, in some circumstances, be strong enough to more than make up for outbreeding depression. Because of this and because of the uniformity and predictable outcome of a first generation hybrid (F1 hybrid) farmers keep purebred strains for the purpose of outcrossing. Crossing the hybrids will give unpredictable outcomes and outbreeding depression will remain or worsen so that is not common practice.
As a general rule of thumb, hybrid vigor (another way of saying a reduction of inbreeding depression) is strongest in first generation hybrids and gets weaker over time. In contrast, outbreeding depression can be relatively weak in the first generation. But outside the context of ruthless selective pressure, outbreeding depression will increase in power through the further generations as co-adapted gene complexes are broken apart without the forging of new co-adapted gene complexes to take their place.
It is important to keep in mind that these two mechanisms of outbreeding depression can be operating at the same time. However, determining which mechanism is more important in a particular population is very difficult.”
So to answer your question – no one really knows! I relate the bass situation to the hybrid bream. The first generation is great, but the F2, F3, and subsequent generations are much less desirable. I don’t think hybrid bass will experience this deterioration to the same extremes or as rapidly, because the parent fish are much more closely related than bluegill and green sunfish. In fact, many would argue that we have precious few pure strain populations left, and many suspect that the world record Georgia bass was an intergrade between the two bass strains.
I tell people that if they already have hybrid bass, don’t worry about it. Manage for food and age and you’ll be fine. However, will selecting a fish to stock, I think the safest bet is to stock a pure strain.
It is very difficult to make predictions about different stocking ratios of pure fish, since bass don’t necessarily spawn randomly. However, if you assume random spawning, a gross approximation of genetic composition (percent of population) following stocking at a 50:50 ratio would be:
Gen 1: 25%F, 25%N, 50%F1 Gen 2: 6.25%F, 6.25%N, 12.5%F1, 75%Fx Gen 3: .39%F, .39%N, .78%F1, 98%Fx Gen 4: 0%F, 0%N, 0%F1, 100%Fx
Hence, by the third generation the reproductive output is primarily Fx hybrids. The stocked fish and the first two generations would provide superior growth for probably 10-12 years or so, but after that you should see the effects of outbreeding depression.
Thanks Greg!! I am not worried about this really, but I do admit that I had not heard or read about it before the conference presentation and I was a bit shocked.
With a typical carrying capacity of 50lbs of bass per acre, assuming 1/2 of those fish are mature females that spawn each season, we have the introduction of up to around 125,000 bass fry per acre per year to that system. Those that hatch early have an advantage (most of the time), but otherwise it is the most fit of individuals that survive and reach maturity. Additionally, with some bass harvest, addition of new genetics, etc, I don't expect outbreeding depression to be a serious player in most cases.
I seem to have stirred up a hornet's nest with this one. As I tried to explain during the talk, this is not a major concern in pond management because genetics are secondary to food, age, and water temperature. However, outbreeding depression is clearly demonstrated in other agriculture. Farmers raise F1 hybrid corn, but they never save the seeds for replanting. Why? Because the subsequent generation does not perform as well. Now bass are not corn, and Florida bass and northern bass are much more similar than the parents of many hybrid species. In reality, we probably will never empiracally test it, since it would take 10 to 20 years to trully demonstrate, and there are too many confounding factors to sort out. I would be more worried about inbreeding depression - that is small gene pool - than outbreeding depression. However, if you would like some follow up reading, I list a few studies that you can check out below. You'll notice similar names on all of the papers because they are the primary researchers working with bass genetics. One study that addressed the potential for outbreeding depression is:
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 D. P. Philipp and M. S. Ridgeway, editors. Black bass: ecology, conservation, and management. American Fisheries Society, Symposium 31, Bethesda, Maryland.
This study did not directly test the outbreeding depression of F1 hybrids but instead it looked at the effect of stocking one genetic stock on the other. However, the mechanism is the same.
Dave Philipp had several earlier papers that addressed the potential for later generation intergrades to have reduced performance:
Philipp, D. P. 1991. Genetic implications of introducing Florida largemouth bass. Canadian Journal of Fisheries and Aquatic Sciences 48 (Supplement 1):58-65.
Philipp, D. P. 1992. Stocking Florida largemouth bass outside its native range. Transactions of the American Fisheries Society 121:688-691.
Philipp, D. P., and G. S. Whitt. 1991. Survival and growth of northern, Florida, and reciprocal F1 hybrid largemouth bass in Central Illinois. Transactions of the American Fisheries Society 120:58-64.
Another paper that I recommend is:
Kassler, T. W., J. B. Koppelman, T. J. Near, et al. 2002. Molecular and morphological analyses of the black basses: implications for taxonomy and conservation. Pages 291-322 in D. P. Philipp and M. S. Ridgeway, editors. Black bass: ecology, conservation, and management. American Fisheries Society, Symposium 31, Bethesda, Maryland.
In this manuscript, the authors offer substantial evidence that suggests "Florida bass" and "largemouth bass" are two separate species.
Think about it, stew over it, but I hope you talk nicely about me in the end
First of all, Im glad people like Dr. Neal are doing these kinds of studies. Its really interesting and helpful for us pond junkies. Thanks Dr. Neal
I like the last paragraph of Dr. Neal's explanation.
"Hence, by the third generation the reproductive output is primarily Fx hybrids. The stocked fish and the first two generations would provide superior growth for probably 10-12 years or so, but after that you should see the effects of outbreeding depression."
What im getting from that is as long as you reintroduce a few pure strain Floridas, or Northerns or even true F1's every year or even every couple years you will be fine. Neal is talking 10-12 years down the road for the originals!!
Am I missing something or is that a correct interpretation?
Im working with right at 50 acres of water here on the ranch with all sorts of goals for each BOW. If I think that I can stock ponds once and not do any corrective stocking for 10-12 years, A) thats just boring and no fun and B) I don't think i would be taking the mananging seriously if I had clear-cut goals to accomplish. To be actively managing a pond its something that you don't just start up and leave, you have to make alterations and in this case New genetics additions to keep your fishery healthy and performing to its max.
Well, so far so good. I cant drag a beetle spin across the pond without getting a hit. I am starting to cull bass and bg after being assured the lmb spawned. the hsb seem to be helping with the sized bg that the lmb have outgrown. plus, they are feedhogs as are the F1s.. I agree with Ewest that the Miss. Biologists that post on the forum are ultra cautious in their recommendations due to their experience that most of the ponds will not be managed the least bit.
Let me answer Dave first - Outbreeding depression can occur in several ways, but the one I am most concerned about is through the breakdown of biochemical or physiological compatibilities between genes in the different populations. For example, Florida bass have genes (genetic material) selected for positive, overall effects that are produced when combined with other Florida bass genes. Due to nonadditive gene action, the same genes may have rather different average effects when combined with northern bass genes. In other words, Florida bass will tend to have genes selected for the quality of combining well with gene combinations common in in othe Florida bass. However, Florida bass genes will not have been selected for the quality of crossing well with genes common in northern populations. Yes, the world record bass was probably an intergrade between the two; but that intergrade had many thousands of years to select for the right genes for its habitat. That is very different than artificially mixing genetic material in the short term.
As for Chadwick71's question, think about it this way. Say you come into a 20 year old pond that was originally stocked with F1s. It is all Fx at that time, and you supplementally stock 10% more bass that are pure Florida. Only 1% of the next generation will be pure Florida, and 99% will be Fx fish, because they are breeding with Fx fish. So you have a limited effect with supplemental stocking. Stocking F1s will give 100% Fx the next generation.
Generation Fl No F1 Fx 20 years 10.00 0.00 0.00 90.00 Gen 1 (%) 1.00 0.00 0.00 99.00 Gen 2(%) 0.01 0.00 0.00 99.99
But for you fish producers, imagine what could be accomplished with a sterile (triploid) F1 hybrid! You could take two approaches. Approach 1 would be to stock only triploid F1s every year and have a completely controlled population with hybrid vigor! Approach 2 would be to establish a Florida bass population and then supplement with triploid F1s - this would maintain genetic integrity while also providing F1s to catch.
Triploids aren't 100% triploid as you well know and so would have to be individually tested as juveniles to weed out the diploids. Those bass may cost around $10 ea by that time.
Then after all that work we may get an accidental introduction of male and female LMB via natural transportation.....then what?
Last edited by overtonfisheries; 09/22/0902:05 PM.
That's fisheries management! The truth is that none of this is that important. If we go 20 years and find out that Fx's are good, no harm no foul. If we find out they are bad, rotenone and start over. That is the beauty of working in small systems. I think F1's can play a role, but it is may duty as a scientist and an Extension educator to make people aware or the potential effects of any management activity. For example, do I think tilapia can escape for a Mississippi pond and establish in coastal rivers? Absolutely! Are they good for bass forage and filamentous algae control in ponds? Absolutely! It is tha job of the pond managers and state wildlife officials to weight the evidence and make decisions.
True, True! I understand. This information has great potential influence on my business and on the decisions of pond owners across the country. I appreciate the insight.
I seem to have stirred up a hornet's nest with this one. As I tried to explain during the talk, this is not a major concern in pond management because genetics are secondary to food, age, and water temperature.
Yes Sir, I believe you may have done just that, helped by our communal ability to agree on 99% of a subject and argue about the 1% we disagree on.
"Live like you'll die tomorrow, but manage your grass like you'll live forever." -S. M. Stirling