Pond Boss Forums STOCKING A NEW POND Types of fish to choose F1 LMB

Many people have discussed very positively the use of a cross between Florida LMB and northern LMB. It seems to me that this would be a very difficult cross to manage.

Whether Florida LMB are a separate species or a subspecies is irrelevant. Essentially, we are creating a hybrid with all of the problems of a hybrid. F1 LMB should operate the same as hybrid bluegill. We should see hybrid vigor the first generation followed by hybrid depression.

Is this thinking valid?

If this thinking is valid, then I would think that fish from northern Florida or southern Georgia would be much more appropriate. Comments please.

Norm :

Fla. and northern LMB are the same species and I have seen no info or studies that indicate any outbreeding depression in/from the crosses F1's F2 or any Fx's. They are not hybrids genetically (like HBG where the parents are genetically different) and the two can cross back and forth with all % mixed up. To the best of my knowledge there are only a very few marker gene locations that allow the determination as to what % of each you have. There has been over 20 years of study and experiments and papers on this matter and I have not seen one that even hints at this being a problem. In addition if this were a problem it would show up in the LMB populations of south GA , north FLA ,south Ala. etc where the populations naturally cross/intergrade into all % of both types. If someone has seen such info please let me know. While I have not seen as much info on BG - CNBG I think the same can be said for them.

I have seen one source that says millions of years ago while south Fla. was attached by a land bridge to the US the populations of LMB and BG were the same and then water levels rose and peninsular Fla was separated from the mainland thus isolating the populations long enough for the slight changes to occur ,then the water level subsided and the populations began to intergrade again. I have been meaning to ask George if that is his understanding of the geology of Fla. to see if the idea is plausible.

FYI, I have been told of some winter kill even on F1 LMB from Arkansas farmers. South Dakota environment would select for northern LMB genetics.

Todd :

No doubt about that. I have seen multi year studies over the US on this and in the far north locations (one in the study was Minn. or Wisc.) none -- 0 -- of the Flas. live through the winters and the ones in Ill. did very poorly (much worse than northerns).

Hybrid vigor and depression shouldn't occur just between different species or subspecies. The basic evolutionary unit is the population. In this case, we are crossing two different populations. That's why we call them F1.

I'm thinking of hybrid seed corn or any other commercial crop. Two varieties are constantly crossed to produce F1 hybrids. Further generations start to show hybrid depression. The two strains crossed certainly aren't different species or subspecies but just two different strains.

Whenever we cross two different populations, we should experience hybrid vigor and depression, just on a smaller scale. This should occur just by crossing anything from the northern and southern parts of a species range.

Is this thinking correct?

Wouldn't most any species, when isolated as in a pond from outside breeders, exhibit depression...independent of whether it is hybrid or not?

LMB whether crossed, not crossed, or "hybrid" are not any different...I expect all will experience "depression" without the introduction periodically of "fresh" bodies.

Sorry I don't have the right scientific words to use, being a rancher, but I see it all the time in cattle. New blood must be introduced to maintain vigor.

With cross-strain hybrids in fish like Norm's FL/Northen LMB example (as opposed to cross-species hybrids like HBG) I suspect the post-F1 hybrid depression is both less severe and less apparent than we might envision (i.e. less worth worrying about). Less severe in that there would, I think, be fewer fatal or debilitating recombinations of genes given that the parent stocks are the same species. Less apparent because a typical pond is a competitive environment for all kinds of fish (even cannibalistic top predators) where slight F2+ disadvantages tend to be weeded out, and severe F2+ disadvantages are harshly culled. (Of course, this latter facet of pond life would also tend to cull the victims of cross-species F2+ hybrid depression.)

To try and explain the "less severe" better, I expect more bad combinations to occur in cross-species F2s because the possible combinations include those missing vital genetic info from one species that is not present in the second species. Where both parents of same species, different strains, I think there is a much higher incidence of the "vital" genetic info being present on both sides of the hybrid tree.

If I'm correct in all this, the corollary would be that cross-strain hybrids should tend to exhibit a lesser amount of F1 hybrid vigor than cross-species hybrids do.

I think FL-Northern F1's planted in any environment will over time be selected for the traits that are suitable for where they are at. If climate were the only selector, the Fx generation would, as x increases, tend to become more Northern-like in say Illinois. The Fx LMB in Georgia would tend to become much more like straight FL bass. In real ponds other factors like fishing pressure and the catchability differences between Northern and FL bass genes would have additional selecting affects that might make as much or more impact than climate.

Does all that make any sense (even if you disagree)?

ML, my mammal experience agrees with you 100%. However, somebody (hey ewest, I probably mean you) posted info 6 months ago or so stating that fish are less affected by inbreeding than mammals are. I can't remember exactly why; I think somehow they have a higher redundancy of genetic material (???).

my head is spinning, Genetics was my hardest A and remember now why I did not like it,

Greg,

I never had the course and my head is really spinning.

Theo,

Now that you mention it, I do recall such a discussion and I believe you are right that it was posted just as you said.

I will check on this some more and post what I find.

There is a natural area across N Fla., Ga., Ala., S.C., Miss. where Fla. LMB and Northern LMB intergrade called the intergrade zone. It has various % of Fla. and Northern genetics from 100% one way to 100% the other way. If there were reduced fitness in these populations it would be widely known. In addition hundreds of fisheries scientists and geneticists across the country have worked on LMB genetics for at least 20 years with no mention of depression occurring in the crosses. For example TA&M and TPWD have genetics data for years on the 2 including the breeding of non reproducing (triploid LMB) . If there were a danger that mixing Fla. and Northerns in Texas lakes would lead to depression of the population I don't think they would have spent untold millions on these projects. Have any of the Texans who have fished the Lakes where TPWD has stocked/added Fla. to a lake with a northern population seen what you thought was reduced fitness in those populations.

I think the 2 strains are to close genetically to exhibit outbreeding depression in the cross populations. Genetic adaptation is different and applies across all populations over time. For example you can take 100% northern LMB from the south and if you place them in a population in Wisc. most will dye the first winter. They are not genetically adapted to that environment. That is why the fisheries scientists say buy locally produced stockers don't go way off and buy them.

Hybrid vigor is defined as the F1 offspring having BETTER traits than either parental species. That is not what you get with a F1 - Fla. x Northern LMB. Instead it has size less than but more like its Fla. parent and aggression less than but more like its northern parent. Enough for now. Will return with more info later.

Theo I think one of the studies I sent you and may have posted about deals with genetic redundancy in sunfishes. I will check on that.

Eric
Recall that the world record largemouth was caught by George Perry in Georgia in the area you mention. It was caught in 1932 in Montgomery Lake --a flooded oxbow off the nearby Ocmulgee River.

Frank

And that 22+ pounder is generally considered to have been an intergrade.

OK Guys it looks like we stepped into the middle of an on going argument between the Fisheries biologists/genetics folks. Norm where did your question come from ? It seems several agendas are clashing among these folks with tons of data I can only make a wild guess about. First very few proven answers but 2 schools of thought but not specific to Fla. Nrth. crosses but to all LMB populations. One side says don't stock any LMB into a distinct population (example not even south ILL. LMB into Nth. Ill lake or a Fla. LMB into a GA. lake) as it causes decreased fitness/outbreeding depression. The other position is the one held by most state conservation folks and that is it has proven to be a useful tool in the right circumstances to stock what appear to be genetically better fish into existing populations. The results are disputed nicely between the groups and both admit there is not enough hard genetic evidence. No dispute between them on the proposition that you should not stock fish from dissimilar environment together (deep south fish to Minn.). These papers were not written as hybrids with hybrid vigor followed by hybrid depression but as outbreeding depression resulting from the loss/reduction of local adaptation. This may be as far as we can go with this topic without other input.

EWEST,

I'm curious, you have a lot of experience in this area, which camp do you lean towards? I think I'm in the "stock what appear to be genetically better fish into existing populations" camp myself...at least in practice and without data. However, if the other side is correct, the implications to a lot of LMB ponds are not pleasing to think about.

Ewest, this is just curiosity spurred by the discussions on GG and other hybrid sunfish species. Yes, this would be outbreeding depression rather than hybrid depression.

It seems to me that using the intergrades would be more useful than F1 hybrids. These intergrades certainly grow large and would be more adapted to more northern environments.

The problem with F1s would be that it would take quite a few generations before a new genetic stability would be reached. With intergrades, the genetic stability has already been reached.

I think that Theo is right, because these populations are closely related, any increase or decrease in different characteristics would be relatively minor. The full range of different characteristics should be produced and then selected for or against.

I guess that my real question is why use F1s when intergrades have already gone through this selection process?

ML and Norm :

Here is where I am on the topic until I see more info. I will keep this simple and not get into the genetic terms and fact situations and differences as they are many. No references to hybrids, intergrades or crosses except wrt where I would not use them. None of this includes the catchability issue.

1. In the south (south of a line from Los Angeles to Columbia SC) Fla. LMB are ok. and so are all % mixes and northerns ( except Fla. south of St. Augustine where only Flas. should be stocked). North of that line but south of a line from Las Vegas to Wichita KA to DC , F1 (Fla/North mixes with 50% or less Fla. genes) are ok as are northerns. North of that line Northern strain only.

2. Stock only fish from close to home. If in Texas and you want Fla. or F1 or northerns get them from a trusted source in your area and verify that the brood stock line has been there as long as possible (the more generations the better). If in the north get your northerns from close to home -- do not stock south Ill. fish into north Ill. ,Minn. , Wisc. etc.

Why those lines? The lakes along them plus the data (to me) say so. Socal lakes ,Lake Fork, Caddo , Barnett , and a SC study indicate Flas. are ok. Studies of the mid area indicate possible problems with Flas. but ok with F1s. ,north of there info says local northerns only.

ML on this point I am with you and the majority of the State agency types and most lake mgt. companies/hatcheries. The other side has good points worth watching closely but is trying to change the accepted methods as it relates to any Fla. genes outside south Fla. or for that matter adding any genes from outside the existing distinct population into it.

One little thing no one has pointed out. With mammals, you have control over hybridization. With seeds, you have control, too. With bass, you might think so, but actually you don't. They eat each other. In theory, cross a Florida with a native and all fish are first generation intergrade, 50% crosses. But, different loci and different genes influence genetic traits. Let's discuss the spawn of one male native strain bass with a huge Florida female. Let's say she has 50,000 eggs. Of those, 45,000 hatch. Of those, 4,500 are aggressive fish, 4,500 are passive and the other 36,000 are considered somewhere in the range of 'normal', behaviorially speaking. Considering each fish has a different set of dominant genes, and a different set of recessive genes, it is interesting to think about the mixes of genes combined with the behavioral nature of individual fish. Size, one would think, is a dominant gene. So, if an aggressive fish, with recessive tendencies of growth, eats a less aggressive fish with genetic potential to reach world record status, does that affect long term expectations of a population? If a tree falls in the woods, does my wife blame me? I have seen, on several occasions, a population of fish rejuvenate with genetic additions, only to begin to decline again in a few years. What really stirs the pot in a fishery is when momma crosses with a son, or a nephew, or a brother. From my anecdotal experience, I believe a population of bass begins to decline after its fifth year. So, in the third or fourth year of many of our ponds, we add fingerlings of known genetic integrity to "add new bulls to the herd."
Also, I have taken some largemouth bass trained to feed, with small amounts of Florida genetics, raised in Oklahoma, to New York. Not only did they survive their first winter, they are involved in their second one. Results as they come available. That landowner's goal is to raise double digit bass. So, with some genetic influence and all the food they can eat, we haved stacked the odds. It's up to nature to teach us if we can honestly fool her.

Finally, Bob Lusk asks a question that I know the answer to!

Some info of interest.

Responses of Northern, Florida, and Hybrid Largemouth Bass to
Low Temperature and Low Dissolved Oxygen
GARY J. CARMICHAEL' AND
J. HOLT WlLUAMSON2
U.S. Fish and Wildlife Service
Route 1, Box 159-D
San Marcos, Texas 78666, USA
COLLEEN A. CALDWELL WOODWARD* AND
J. R. TOMASSO4
Aquatic Station
Southwest Texas State University
San Marcos, Texas 78666, USA
Abstract.—Two parental subspecies of largemouth bass
(Micropterus salmoides), northern (M. s. salmoides) and
Florida (M. s.floridanus), and their reciprocal F, hybrids
were examined for their responses to low temperature
and low dissolved oxygen concentrations. The four strains
(verified electrophoretically) survived a temperature decrease
from 21 to 1°C at a rate of about l°C/d followed
by immediate warming. Among fish maintained at low
temperature (2.0 ± 0.4°C; mean ± SE) for 5 d, mortalities
were 48% for the Florida fish and 4-5% for the
Florida (female) hybrid, compared with zero for the
northern fish and the northern (female) hybrid. All four
groups showed similar trends in feeding behavior during
the temperature treatments.

Will the northern (female) hybrid grow as large as the Florida (female) hybrid? If so, and this data is accurate, it would seem that the northern (female) hybrid would be a better choice for us notherners.

Bruce :


I will get some info together. In short all things being equal the North (f) x Fla. (m) are smaller than the reciprocal cross. That is why the F1s from the hatcheries that produce ( tiger or tigre bass for Todd's variety) cross Fla. (f) x Nort. (m). Many don't know that the Fla. males are small relative to North. males and as a % of Fla. females. So if you stock Flas. half your fish (males ) will be small in comparison. Anyone thinking about stocking LMB with Fla. genetics of any sizable % north of the northern line described in my post above should seriously check the info first. From what I have read they just do not grow to their potential and under perform North. strain. Where is the % cut off -- I don't know. Bob may add new info with his NY experiment.

Our experience with mammals can't be transferred directly to fish, but ask any experienced rancher or Vet in East Texas about buying cows and horses from outside this area to stock on local ranches and they will tell you it is a big mistake. The environment here is different and creatures not adapted to that environment have a lot of trouble.

It will be most interesting to see what Bob's results are in NY...if anyone can do it, he can.