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#541880 12/02/21 09:36 PM
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Was thinking I would buy fish from here as its on my way. Snrub has purchased from them and been very satisfied. The question I have is about CNBG. Do they produce populations that are 80% female? I google a few carefully constructed search to see if I could find more on this. I am very skeptical. Most populations of NBG that I am familiar with are biased (based on creel) towards males so this caught my attention. Does anyone have any thoughts on this? Or can point me to good reading on the subject?

http://www.dunnsfishfarm.com/coppernose_bluegill_246_prd1.htm


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They got it backwards - it's more like 80% male.

ewest can point out several studies confirming.


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Neither CNBG or BG have disproportionate male/female ratios. They do change a bit (minor imbalance based on situation). It is the Lepomis crosses that have disproportionate sex balances (but not all). Dunns ? They may be describing HBG but got the ratio backwards.

From an old Cutting Edge PB article - if you don't - all you guys should subscribe to PB magazine.

THE CUTTING EDGE – SCIENCE REVIEW



Coppernose Bluegill vs. Regular Bluegill – which one for you?


A question we often get on the Pond Boss Forum is should I stock Regular Bluegill Lepomis macrochirus macrochirus or Coppernose Bluegill Lepomis macrochirus mystacalis also previously classified and referred to as Lepomis m. purpurescens . To answer that question we should look at the traits of both and use the one that will work best for the particular goals for the water in question. As we all know traits come from genetics. So what is the difference in the genetics of Coppernose vs. Regular Bluegill? Well it started a long time ago and it took a long time to get there. Here is the basic story. Millions of years ago peninsular Florida was, like it is today, connected to the mainland. Bluegill were present all over the eastern US. Sea level rose and peninsular Florida was cut off by the sea from the mainland creating two separate populations. Bluegill on both the mainland and on the peninsula continued to evolve separately each influenced by local conditions with a divergence time of roughly 2.3 million years. After a few million years of this separate path sea level fell and the two land masses were connected again. However the two bluegill sub-species were now a little different genetically. The rivers were connected and the two subspecies migrated and integrated in a zone along the deep southeast where the two sub-species mixed. If this sounds familiar it should – it’s the same story as the Florida Largemouth Bass and the Northern Largemouth Bass where the divergence time between Northern (M. salmoides) and Florida (M. floridanus) bass is approximately 2.8 million years. If you know one story you should have a fairly good idea of outcome of the other. Surely as a pond owner you have heard the bass story. Florida Bass get bigger under the proper circumstance and do not due well in cold climates. Yes Bluegill have a similar story.

Coppernose Bluegill get bigger under the right circumstance but do not flourish in colder climates. In fact Coppernose are susceptible to poor results and substantial winter kill in northern US regions as are Florida Largemouth Bass. So how do you tell Coppernose and Regular Bluegill apart. Take a look at the pictures included. The Coppernose has a copper band across its head/nose in adult males, has fewer and wider vertical bars, has orangish/red fin margins and tail coloration , 12 anal fin rays and often light/white fin edges most visible when young. The Regular Bluegill has 11 anal fin rays and none of the other traits mentioned.

So how do they compare? Here are some points from a study on the subject titled Performance Comparison between Coppernose and Native Texas Bluegill Populations by John A. Prentice and J. Warren Schlechte in the 2000 Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies , Vol. 54 at pgs 196-206 looking at growth (size at age) , survival and catchability.

Coppernose Bluegill were significantly larger than Native Bluegill in all scenarios tested with the largest observed difference being 19.2 mm total length (.756 inch) and 33.5 grams ( 1.18 ounces) over 2 years. At 3 years there was a 16 mm (.63 inch) difference on average and at 4 years 24 mm (.945 inch). With other fish species present there was no difference in angling vulnerability between the types. Spawning activity of the brooders began at the same time (last week of Feb in 1995 and first week of March in 1997) and produced the same size offspring for tagging at the same time each year ( mid-April) in what appeared to be similar numbers. Survival of young of the year Coppernose was substantially greater than for Native Bluegill.

Before you draw to many conclusions note this was in Texas where the weather is close to that of the Coppernose’s native range. That is a critical key to success with Coppernose. While there is an often cited study titled Cold Tolerance in Two Subspecies of Bluegill by , A. J. Sonski , K. E. Kulzer , and J. A. Prentice, in the 1988 Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies , Vol. 42 at pgs 120-127 , that states Coppernose and Native Bluegill have similar cold tolerances the key is the test was done on bluegill all from the same area (Texas). Its purpose was to determine if Coppernose could survive the Texas climate. There is substantial observed and anecdotal evidence that Coppernose do not do well in cold climates (roughly north of the north line of Arkansas/Tennessee extended) . In the far northern US Coppernose become subject to high winterkill rates. This would be consistent with their similar relationship to Florida Largemouth Bass which have repeatedly been tested to do poorly and die in cold climates. The study first cited above was also in ponds with no supplemental feeding. Reported scientific evidence is substantial that in ponds the most common cause of reduced growth is a shortage of food. It is not known how much, if any, of the early growth difference between the two sub-species was due to limited forage. The two sub species will integrate (inter-breed) with the offspring exhibiting mixed traits and no apparent negatives but there is very little published data on them.

So the answer to the question should I stock Coppernose Bluegill or Regular (native) Bluegill or both is – it depends. Your location (climate) and your goals are key factors. If you are in the Deep South or the Southwest (including Southern California) and not at high elevation (Appalachian, Rocky or Sierra Mountains) Coppernose should be considered. In short is your temperature profile similar to those areas? To some extent management practices and the existing bluegill population, if any, are also possible factors. Whichever type you choose keep in mind that the most important factor to growing nice bluegill is to be sure they have enough food to eat and not to much competition.

Last edited by ewest; 12/03/21 10:30 AM.















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I'm with ewest, no disproportionate male/female ratios.


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I will add however that in later sampling one often finds imbalance (which is natural) due to survival issues. So, studies showing imbalance in ponds when seined or drained and counted are based on survival and population factors to that site. Often there can be more females than males (natural) but that is not due to spawning imbalance (genetics).
















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That's my sense too. The swim up is balanced but environment effects can alter the proportions. May not be the case with CNBG but one reference showed that the growth rate of male NBG is twice that of female NBG. So I have always wondered if this may help males survive to adulthood better.


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It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers


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Slightly off topic,

What is the evolutionary advantage for sexual dimorphism related to size?

In LMB the females grow significantly larger, in BG the males grow larger. Both are members of Centrarchidae, so their basic biology is similar.

I find it strange that the species have opposite responses to their environment. Obviously, their ecologic niches ARE NOT the same.

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Originally Posted by Theo Gallus
They got it backwards - it's more like 80% male.

ewest can point out several studies confirming.
Boy did I screw that up. I saw "CNBG" and read "HBG".

Time for my Geritol.


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Originally Posted by FishinRod
Slightly off topic,

What is the evolutionary advantage for sexual dimorphism related to size?
. .... Obviously, their ecologic niches ARE NOT the same.

If interested there is a lot out there on Centrarchidae. Neff did a lot of published work on BG which opened a lot of eyes. Keep in mind that BG have alternative reproductive species survival methods - males of alternative life histories. in his studies, Cuckolder males mature precociously at 2 years of age while normal parental males sexually mature at about 7 years of age. Nothing like this in LMB as an alternative survival method.

[Linked Image]

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BG alt LH Capture.PNG (165.02 KB, 136 downloads)
Last edited by ewest; 12/06/21 10:26 AM.















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ewest,

Thanks for that additional information so I can do some follow-up research.

Nature is endlessly fascinating!

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Here is another good reference book from AFS


[Linked Image]


and some info on CENTRARCHID FISHES

TEMPO OF HYBRID INVIABILITY IN CENTRARCHID FISHES
(TELEOSTEI: CENTRARCHIDAE)
DANIEL I. BOLNICK1,2 AND THOMAS J. NEAR3,4
1Section of Integrative Biology, University of Texas at Austin, 1 University Station C0930, Austin, Texas 78712-0253
2E-mail: danbolnick@mail.utexas.edu
3Department of Ecology and Evolutionary Biology, University of Tennessee, 569 Dabney Hall, Knoxville, Tennessee 37996-1610
4E-mail: tnear@utk.edu
Abstract. Hybrid viability decreases with divergence time, a pattern consistent with a so-called speciation clock.
However, the actual rate at which this clock ticks is poorly known. Most speciation-clock studies have used genetic
divergence as a proxy for time, adopting a molecular clock and often far-distant calibration points to convert genetic
distances into age. Because molecular clock assumptions are violated for most genetic datasets and distant calibrations
are of questionable utility, the actual rate at which reproductive isolation evolves may be substantially different than
current estimates suggest. We provide a robust measure of the tempo at which hybrid viability declines with divergence
time in a clade of freshwater fishes (Centrarchidae). This incompatibility clock is distinct from a speciation clock
because speciation events in centrarchids appear to be driven largely by prezygotic isolation. Our analyses used
divergence times estimated with penalized likelihood applied to a phylogeny derived from seven gene regions and
calibrated with six centrarchid fossils. We found that hybrid embryo viability declined at mean rate of 3.13% per
million years, slower than in most other taxa investigated to date. Despite measurement error in both molecular
estimated ages and hatching success of hybrid crosses, divergence time explained between 73% and 90% of the
variation in hybrid viability among nodes. This high correlation is consistent with the gradual accumulation of many
genetic incompatibilities of small effect. Hybrid viability declined with the square of time, consistent with an increasing
rate of accumulation of incompatibilities between divergent genomes (the snowball effect). However, the quadratic
slope is due to a lag phase resulting from heterosis among young species pairs, a phenomenon rarely considered in
predictions of hybrid fitness. Finally, we found that reciprocal crosses often show asymmetrical hybrid viabilities.
We discuss several alternative explanations for this result including possible deleterious cytonuclear interactions.
Speciation-clock studies have been a small cottage industry recently, but there are still novel insights to be gained
from analyses of more taxonomic groups. However, between-group comparisons require more careful molecular-clock
calibration than has been the norm.

Last edited by ewest; 12/06/21 07:19 PM.
















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