Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Pros and cons of HBG?

What would be the pros and cons of stocking some HBG in a pond already established with native BG?

Those pictures on this site of 10 Mo old HBG got me wondering.

FH

Biggest drawback in my opinion would be introduction of green sunfish genes in to the BG gene pool.

BG and HBG don't mix well genetically or competitively. The HBG are 90% +- male and compete with the male BG. There is uncertainty if HBG can backcross with BG and if so what the result will be.

The main advantage to HBG is their ease of catching and secondarily their early growth rate. This may not apply well when mixing BG and HBG.

Not something I could suggest.

The growth advantage of young HBG (over young BG) is probably due to mouth size. Putting HBG in a pond with adult BG would negate this.

In my sampling study of 2006, I collected fish from a closed, non-flow-through, very private access, 1/3 ac pond that I originally stocked with a low density of Hybrid Bluegill(18)(bluegill x green sunfish cross) and yellow perch(120) back in 1989. Predator fish has been SMB. Sampling by angling yielded 5 large HBG (8"-8.9")whereas various traps produced 25 small fish that I called green sunfish some of which are in the photo below.

There has been previous discussion and various opinions, some it from learned individuals, on this forum about what the resulting fish will be after numerous generations of HBG reproduction. My experience in this one pond is that after 16-17 years I am seeing green sunfish. I did not and have never caught any fish from this pond that I would call a bluegill; I occassionally catch HBG types but never a fish that has closely resembled a bluegill. The picture is not the best quality due to my photographing the fish in a laundry basket. If anyone wants better photographs of the small sunfish types from this pond I can easily get more photos this summmer.

Thanks Bill. I will put this pic in the HBG thread as you noted GSF.
Eric, I fixed the HSB-HBG error in my post above. Thanks catching my error.

That is very interesting!! Two reasons, first,I had heard the off spring of the HBG was nondesirable several years ago, prior to my owning a pond so hadn't really considered it until I saw all the photo's of these big HBG som of you were posting, it was making my mouth water, so thank you.

Second, when I first started looking at the pond I eventually bought it was absolutly loaded with GSF and stunted LMB, I actually sought the help of IADNR for eradicating the whole pond. I don't know the stocking history so couldn't say but possibly this could have been the case with my pond. Fortunatly the 1999 year was one with an extended snow cover of 12" for most of the winter, this would be the only reason I can come up with in the dissappearance of the entire ponds fish population. Saved me $500 on Rotenone!

Thank you for the discussion and comments, it may have just saved me a headache.

FH

Fishhead, my experience is exactly the opposite of Bill's. I originally stocked the same amount of pure green sunfish as bluegill and about 1/4 that amount of HBG. The difference in our ponds is the predator. In addition of SMB, we have LMB. I think this has made all of the difference.

Even though we actually stocked pure green sunfish, they are virtually gone from our lake now. These fish were stocked in 2000. We have had an almost straight line decrease in green sunfish.

We have never sampled, in any manner, young HBG even though I've seen them actually bring off a hatch. I've always thought that the HBG would dominate the spawning beds. At least in our experience, this hasn't happened. Maybe ewest can shed some light on this. It appears that HBG look different enough from pure BG that given a choice, the female BG choose male BG.

I personally love HBG but know that we will loose them unless I can find some big enough to survive LMB predation. For me, it isn't an either/or situation with HBG and BG. I like them both. It's a matter of being with LMB, we don't get any HBG reproduction.

BAIT!

Bill, were these the standard hatchery raised HBG, male BG X female GSF cross? The reason I ask is that seems to me the resulting male offspring tend to take on more of the physical characteristics of the female than the male in appearence. Over time I suspect these slightly more dominant charateristics would become more prevlent in subsequent generations of offspring. It makes me wonder if a female BG X male GSF cross would look more like a BG in subsequent generations. I am probably all wet on on this one but it's something to think about since the other type of hybrid is not readily offered by most hatcheries.

Shorty - Cody says the hybrids came from a hatchery but he is not sure of which species was the male. Not all hatcheries use the same male female combination.

Good question, Shorty. There is I believe more female influence on hybrid offspring due to their being the sole source of mitochondrial DNA (I'm guessing fish have that like mammals) and due to the fact that the egg has physical properties affecting the cross (mammalian equivalent might be mom vs. pop sizes - Great Dane x Chihuahua is difficult either way, but carrying the pups is much safer for the mother if she's the Great Dane).

My personal guess is that the management practices and predator load in the pond would have more affect on out year Fx appearance than whether the BG or GSF was the mother.

That was the entire premise of this thread on HBG.

http://www.pondboss.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=5;t=000439

The reciprocal cross in many lepomis is not the same as is the case in many centrarchids.



The std hatchery HBG look more like BG than GSF so I don't know which cross would produce Fx that look like Bill's GSF above.
Bream, Hybrid - Ark. Game and Fish
The hybrid bream is a hatchery cross between a male bluegill and a female green sunfish. The resulting fish exhibits characteristics of both parents. It's not quite as deep in the body as the bluegill but is deeper bodied than the green sunfish. The mouth is larger than the bluegill but smaller than the green sunfish. The color markings have no distinct patterns as do the parents, and hybrids may appear speckled or mottled.

The Hybrid Bluegill is crossed between a male bluegill and female green sunfish. - Dunn's


I don't think management practices or predator load would affect HBG/GSF/BG appearance but would affect if any survived ,unless that could effect the genetics as a result of all of one kind being eaten and the other not. Their growth most certainly will be effected by both. I need to check on more answers wrt what controls sex and size of the cross but IIRC female/male determine some things and the species of the greater size determines others.

Here is some info. Who can decipher it wrt this issue. I think part of the answer is there.

From
TEMPO OF HYBRID INVIABILITY IN CENTRARCHID FISHES

(TELEOSTEI: CENTRARCHIDAE)

DANIEL I. BOLNICK AND THOMAS J. NEAR


Finally, we found that reciprocal crosses often show asymmetrical hybrid viabilities.

We discuss several alternative explanations for this result including possible deleterious cytonuclear interactions


"Amore likely explanation is that Haldane’s rule, an important mechanism of postzygotic isolation, may be weak or absent in centrarchids. Theory suggests that hybrid fertility and inviability should evolve more quickly in taxa with larger X chromosomes and slower in taxa with smaller ones (Orr and
Turelli 2001). This is because the size of the sex-specific chromosomal region determines the number of hemizygous recessive alleles that can interact with dominant autosomal loci to produce hybrid dysfunction (Turelli and Begun 1997).

Karyotypic analysis of centrarchids failed to find karyotypically distinct sex chromosomes (Roberts 1964; but see Becak et al. 1966). A more recent study found evidence that centrarchid males are the heterozygous sex (Gomelsky et al. 2002), but did not assess whether this heterozygosity is limited to one or a few loci or extends to a large fraction of one
of the 48 chromosomes (still a small fraction of the total genome). In some fishes the difference between male- and female-determining chromosomes is restricted to a few hundred kilobases or fewer of male-specific sequence (Kondo et al. 2003). The heterogametic sex is therefore hemizygous for very few loci, reducing the potential for deleterious epistatic interactions between a recessive X allele and an autosomal
locus (Turelli and Begun 1997; Orr and Turelli 2001). As a result, Haldane’s rule will not apply in fish such as centrarchids with little or no hemizygous genome. Because the incompatibilities producing Haldane’s rule are expected to evolve relatively quickly (Orr and Turelli 2001), and contribute strongly to postzygotic isolation in many groups (Coyne and Orr 2004), the absence of Haldane’s rule in centrarchids may explain their slower evolution of genetic incompatibilities.


Asymmetrical F1 viabilities may also result from deleterious interactions between the maternally provided oocyte cytoplasm and the hybrid’s nuclear genes. Centrarchid hybrids show aberrant timing of allozyme gene expression during early development, even when the parental species have
identical onset of gene expression (Phillip et al. 1983). These results suggest that centrarchid species have diverged in their gene regulation mechanisms even while expression location and timing remained similar. In many cases, hybrids expressed maternal alleles at the normal time, but paternally derived alleles were delayed, premature, or failed to be expressed
at all (Phillip et al. 1983). Less viable hybrids in a reciprocal cross are generally the ones with greater paternal allele misexpression. Whitt et al. (1977) suggested that the greater effect on paternal alleles is evidence for cytoplasmicnuclear interactions, hypothesizing that maternally encoded regulatory signals are misinterpreted by the paternal allele. If one species’ gene expression is more sensitive to changes in transcription factors, asymmetries will result.

We do not currently have enough information to distinguish between sex chromosome, mitochondrial, or cytoplasmic
effects. However, the lack of distinctive sex chromosomes (Roberts 1964; but see Becak et al. 1966) suggests that the hemizygous nuclear region is likely to be small (possibly even a single locus) and so may not contribute strongly
to inviability (Turelli and Begun 1997). One puzzling pattern to emerge from our data lends some credence to a role for cytonuclear interactions: using maximum body size as an
index (Page and Burr 1991), the larger species tends to be the more successful maternal parent (Table 3). Of the 18 species pairs with reciprocal cross data and nonzero viability,
one pair had equal body size and nearly symmetrical crossing success. Focusing on the remaining 17 species pairs (admittedly not phylogenetically independent; Table 3), the larger parent was more successful in 13 crosses and less successful in four crosses ( 5 4.765, P 5 0.029). We speculate that 2 x1 there is greater disruption of paternal allele expression when the paternal allele is from a smaller species, placed in an egg with cytoplasmic factors encoded by a larger maternal species.

However, the cytoplasmic effect cannot be attributed to differences in egg size, as egg size is not correlated with body size (D. I. Bolnick, unpubl. data) and egg size differences
are not associated with inviability (Merriner 1971b).

We are working on expanding our dataset to include more reciprocal crosses to test this pattern more rigorously.


In centrarchids, postzygotic isolation can take the form of reduced hatching rates (Childers 1967), developmental abnormalities
(Whitt et al. 1972), larval mortality (Childers
1967), failure to develop gonads (West 1970), altered spawning behavior (Clark and Keenleyside 1967), meiotic failure leading to triploid progeny (Dawley et al. 1985), a biased hybrid sex ratio (Childers 1967), and inviabile or infertile backcross or F2 progeny (Dawley 1987). Gametic isolation does not appear to play a major role in isolation among centrarchids, as fertilization success is greater than 90% (relative to homospecific crosses) for nearly all nodes (West and Hester 1966; Merriner 1971a) and is not correlated with genetic divergence. Hybrid viability, analyzed in this paper, is thus an underestimate of the total postzygotic isolation. For instance, L. macrochirus 3 L. cyanellus show a 99% hatch rate relative to homospecific crosses (range: 79–140), and so do not appear to have begun to accumulate isolation. Yet from 68 to 97 percent of the progeny are male, with varying degrees of fertility due to a high frequency of unreduced (4n) sperm (Wills and Sheehan 2000). While hatching viability is greater than zero even at 33.59 million years, we have not been able to find any documentation of F1 fertility for taxa more than 14.64 million years apart (Fig. 7).

Note that the male-biased sex ratios in Lepomis hybrids do not provide evidence for Haldane’s rule. Since Lepomis hybrids with close to 100% males show close to 100% viability, we can reject the idea that mortality of (hypothetically heterogametic) female zygotes produced the sex ratio. "

Thanks ewest, even though I am not sure I completely understand it.

Can't get enough about cytonuclear interactions!

Me either Shorty.

I get the drift but not the deleterious interactions and genetic incompatibilities .

When one of my old girlfriends dumped me, I experienced postzygotic isolation and all the associated developmental abnormalities ! Woe is me.

hey,Bill whats going on? I can finally send a photo to the form I still can't figure out how to type a message around the pic but, it works and thats all that matters. I just want to thank you and everyone else here on the form for helping me out so much with this.