Thoughts on smallmouth predation to keep bluegill numbers in check.

[Bruce Condello]

I spoke with my Dad yesterday, and he's very much on board with the idea of acquiring smallmouth bass as a predator to keep bluegill numbers under control in his pond. Conventional wisdom says that smallmouth, with their smaller mouth gape, and smaller general size will have trouble keeping up with reproduction. I believe this to be true, but in my Dad's pond we will be able to run a seine at least once, and maybe twice a year to cull out slower growing bluegill and to thin their numbers. I've become rather adept at identifying fish that are thriving, and I think I could take out and relocate slower growers. This "two-pronged" approach should allow us to keep bluegill numbers in check so we can grow as big a bluegill as possible. I'm not really excited about ever adding largemouth bass, because they will be almost TOO good at eating bigger bluegill as they reach sizes that we could eat. My Dad would like to harvest fish from the pond, and we think that heavy harvest pressure on female fish will be an ideal scenario. We get the best of both worlds. Bluegill to eat, and bluegill to grow to trophy proportions. One other advantage to smallmouth is that they are maybe a little more likely than largemouth to utilize some of the pelleted feed.

[Bill Cody]

One topic that hasen't been discussed or utilized much is alternative forms of BG hybrids (HBG). Typically the standard HBG is the BG green sunfish cross (BGxGSF). Since the GSF has the largest mouth of all the Lepomis species the resulting F1 HBG posess aggressiveness, a relatively large mouth and relatively rapid growth. This can be detrimental or a positive for some fish management philosophies. Other features of the standard HBG also make this fish sometimes undesirable.

Not a whole lot has been done with alternative parental crosses of the sunfishes for specialized applications. In specialized types of fisheries where a low fecundity HBG with a smaller mouth or other beneficial traits would desired then other genetic crosses of sunfish would maybe in order. An example would be a BG redear sunfish cross - BGxRES which failed to produce abundant F2 generations. Another good potential cross would be BG pumpkinseed cross which usually produces an abundance of F1 young. These fish are intermediat between a PS and BG, have a small mouth, are predominately male and colorful good growers. A reported disadvantage was its ability to reproduce in later post F1 generations. Specialized demand for "odd" hybrid BG is low thus they are primarily for the popnd boss experimenter.

To produce your own hybrid sunfish it can be done in a very small pond less than 0.1 ac.

[Bill Cody]

Additional ways to reduce or control reproduction.
8. Building the pond with very steep sides to reduce spawning sites. Limited size of spawning area for BG results in fewer nests. Fewer nests = fewer fry produced per yr. Isolated nests or low numbers of nests comprising a nesting colony results in more natural predation of eggs and fry thus reducing numbers recruited. BG nesting behavior has evolved to favor recruitment of fry that are produced from the center of the colony. It has been proven that isolated BG nests and those at the periphery of the colony are much more vulneable to nest predation. Important predators of BG eggs are other BG, crayfish, snails, and for fry YOY bass and other common small fish, predacious insect larvae, and Hydra.
9. Periodic manual destruction of nests by dragging a rake or homemade drag through the nesting area. this should be done every week esp during the height of the spawning season.

[Bruce Condello]

The point is well taken. I'd first want to list all of the ways that we can control reproduction.

1. All male bluegill ponds
2. High density predators, such as low Wr, mid-sized largemouth bass
3. Triploidy (not currently available in bluegill)
4. Angler harvest (not practical in a lot of situations)
5. Trapping
6. Seining
7. Use of a similar species, with lower reproductive potential such as redear sunfish. The foremost disadvantage to this species is the fact that it is less likely to feed train. They also don't thrive as well in cooler waters.

Any others we can think of? These would seem to be all we've got to keep bluegill numbers down so we can grow big bluegill.

[Bill Cody]

Let's discuss this. Why go to all the effort to genetically develop a low fecundity BG when we have the option of using male BG for stocking into ponds where low numbers of pure strain BG are wanted. If that pond needed appropriate sized forage fish to feed some sort of 'special' predator then why not stock a species that would meet those needs. What is needed in a scenarios such as this is a good knowledge or homework of biology of species. 1./ What am I missing in this need for low fecundity BG? 2. Don't we already have the low fecundity feature in RES and HBG? 3. Are those individuals so bad compared to pure stain BG? 4. What are their negatives compared to BG in our scenario?

[Bruce Condello]

That's never crossed my mind. How would you do it? Even if females could be bred to have half as many eggs, it would still be way more than enough to have abundant year classes every year. I suspect it would have to be accomplised on a molecular level with the DNA. Probably through pressurizing the eggs as is done with grass carp? Hmmm.

[Theo Gallus]

You know, I'd like to run another BG pond someday without LMB, but with darn near every other kind of predator that will live in my climate - SMB, walleyes, HSB, and maybe YP as an in-between-predator-and-forage-base fish. I guess since I likely won't be able to swing it until I'm older, with no kids at home and retirement looming, I could figure on being able to apply lots of angling pressure to help control the BG.

Bruce, can you think of any way to selectively breed BG so as to lower fecundity?