Save the Big Male Bluegills!

[Avid Angler]

Hi everyone,

I learned something interesting about the bluegill the other day and I wanted to pass on the information to you all. I think if more of us are aware of this, we could potentially improve the quality of our bluegill fishing in the area.

The big thing when you are out fishing for bluegills is know which ones to keep and which ones to let go.

So this summer as a person is fishing the spawning beds of the bluegill or anytime for that matter here is what you would want to do in order to help increase the size structure in the lake.

Basically, you want to throw back the big mature males that have a large ear flap or ear tab, black in color and extended posteriorly (tailward). Vivid coloration and burgundy colors on breast. Lots of black tips on scales.

These fish have good genetics and need to be released in order to pass on their traits.

You are keeping fish to eat, you want to keep the smaller males and the females. It is ok to keep some females because bluegills are very prolific spawners and will spawn two to three times a summer. If you can keep the smaller males, those are fish you want out of the lake.

The small males look like females and when the big males aren't close to the nest, they go and deposit their sperm, which passes on the small traits.

Study the pictures from the link and learn to tell the difference between them.

Of course there other factors that help to grow big bluegills, but this is what private pond owners do to grow pounders in their ponds. Up until a few weeks ago, I didn't know the difference, but I am definitely going to be more choosy this summer of what I keep.

So I hope this helps educate my fellow fishermen and maybe we can have a few lakes around here with bluegills over 8 inches.

Avid

[Big E]

+1

This has been studied and proven definitively. Keeping larger male bluegill is the key reason for stunting. If you keep the larger males, the smaller males sexually mature more quickly to fill the void, and divert energy into reproducing rather than growing. I can dig up the studies and post here if people are interested.

It's hard for folks to swallow... but keep those fish 7-8". Let those fish 9" and bigger go. Nothing wrong with doing that - in fact, it should be applauded, not looked down upon for keeping "small" fish.

[blakeb]

Boy aint that true good post,

Now if only we could get a strickly Catch and release lake!

That could produse some nice pics.

[Tom7227]

Sorry but I can't see the link. Repost it please.

[mainbutter]

I just wanted to reiterate what the OP said(good post btw!):

It's all about natural selection. It's been shown in both aquarium and pond settings that removing the ~5% largest fish from the system annually creates a significant genetic disposition towards smaller, stunted fish in as little as 3 generations.

the "7 year cycle" I've read some lakes have for panfish sizes makes a lot of sense to me in relation to those studies. Natural selection is a powerful thing.

[Burnham]

a strictly catch and release lake sounds good but is not the answer. if a lake is strictly catch and release, then the males with the genetics to be small will reproduce and eventually take over the lake. the fish with the smaller genetics mature earlier than the ones with the good genetics, therefore they will be reproducing more often and this will phase out the males with good genetics. getting the males with the bad genetics out of the gene pool is the best answer.

[Big E]

Here are the studies I referenced...

Effect of Population Size Structure on Reproductive Investment of Male Bluegill

Male Reproductive Competition and Sex-Specific Growth Patterns in Bluegill

A Comparison of Bluegill Reproductive St...ing Intensities

[Big E]

a strictly catch and release lake sounds good but is not the answer. if a lake is strictly catch and release, then the males with the genetics to be small will reproduce and eventually take over the lake. the fish with the smaller genetics mature earlier than the ones with the good genetics, therefore they will be reproducing more often and this will phase out the males with good genetics. getting the males with the bad genetics out of the gene pool is the best answer.

It doesn't quite work that way. Keeping smaller fish is fine too. The point is that if a lake is left undisturbed from angling, the environment favors bigger bluegills because they have an overall reproductive advantage. Bigger males get the best nesting spots, are better at defending the nest, etc. When they are harvested, that's when conditions favor smaller fish filling the void.

Given the choice, keeping smaller bluegills is the way to go if the desire is for larger fish.

[CalamityJohn]

Big E, maybe it is just me, but I can't get the articles to open up. Do need to be a member of that HSOforum to view them?

[Jim Almquist]

Big E, maybe it is just me, but I can't get the articles to open up. Do need to be a member of that HSOforum to view them?

CJ here is the articles

Although a goal of fisheries management is to understand factors affecting the growth rate and size structure of exploited populations, the relation between growth rates and variation in reproductive behaviors in Lepomis species has received little attention. Allocation of energy to reproductive functions (e.g., gonadal maturation, gamete production, nesting and spawning activities, and brood defense) negatively affects growth rate and, ultimately, maximum body size. To assess how social factors influence energy allocation, we manipulated population size structure of male bluegills L. macrochirus in experimental ponds and evaluated individual reproductive behavior and testes development. We predicted that smaller parental males would invest less in reproduction in the presence of larger parental males than they would in their absence. Observations were consistent with this prediction; smaller parental males had smaller testes and nested less frequently in the presence of larger males than in their absence. Furthermore, when males of both size-groups occupied nests, larger males were more successful. Size-selective angling that removes larger males may, therefore, negatively affect the size structure of Lepomis populations by creating conditions under which smaller, and often younger fish, mature sexually and reproduce. Under those conditions, growth rates would slow at younger ages, and the maximum size attained by these fish would be reduced.

A comparative study of populations of bluegill Lepomis macrochirus from 12 southern Wisconsin lakes was conducted to examine the social and reproductive factors associated with variation in growth rates, and to determine whether changes in growth rates and the relative abundance of alternative male mating types could be attributed, in part, to adaptive changes in bluegill life history parameters. Actively spawning colonies were encircled with 46-m-long seines to collect nesting parental males, reproductive females, and precocial males (cuckolders). Scale samples were used to back calculate size and estimate age of first maturation. Morphometric image analysis was used to quantify the degree of sexual dimorphism within populations. Adult parental males were more likely to exhibit reduced growth rates after maturation than females. In addition, adult parental males from lakes containing stunted populations matured at younger ages than males from lakes with populations that were not stunted. This shift in the age of maturation was correlated with a reduction in sexual dimorphism and the intensity of male competition for nesting sites. The abundance of alternative male mating types was inversely related to the intensity of male sexual selection, with cuckolder abundance reaching nearly 60% of reproductive males within colonies from the most stunted populations. These changes in sex-specific life history patterns are in accord with current theory on the evolution of life history patterns. At least two factors may be responsible for the observed shifts. Increased availability of nesting habitat in shallow littoral lakes may reduce competition among males by allowing less competitive males to acquire territories. Alternatively, sex-specific angling practices that remove large males from nesting colonies may allow younger, less dominant males to move into colonies and successfully spawn. These findings suggest that removal of nesting males will have the greatest effect on male growth in lakes with small amounts of pelagic habitat and where bluegill nest in numerous small colonies.

Life history theory suggests that maturation schedules of male bluegill Lepomis macrochirus and the occurrence of alternative male reproductive strategies (i.e., parental or cuckolder) may contribute to the development and duration of undesirable bluegill population size structure (few fish larger than 150 mm). To investigate this relationship, we assessed parental male maturation schedules and relative abundance of cuckolders in six lakes subject to differing levels of fishing effort. Bluegills were collected by electrofishing shortly after the onset of the spawning season. Lakes with lower fishing effort had parental males that were older and larger at maturity than parental males in lakes with high fishing effort. Also, growth of parental males in lakes with low fishing effort was faster at older ages, and growth of immature males was faster than growth of cuckolders. Unlike other lakes, two of the three low-fishing-effort lakes had very few cuckolders. Our results indicate that intense fishing effort is associated with younger ages and smaller sizes at maturity for parental male bluegills. Also, increased proportions of cuckolders may be associated with increased fishing effort.

[CJH]

+1

This has been studied and proven definitively. Keeping larger male bluegill is the key reason for stunting. If you keep the larger males, the smaller males sexually mature more quickly to fill the void, and divert energy into reproducing rather than growing. I can dig up the studies and post here if people are interested.

It's hard for folks to swallow... but keep those fish 7-8". Let those fish 9" and bigger go. Nothing wrong with doing that - in fact, it should be applauded, not looked down upon for keeping "small" fish.

+2

[Burnham]

oh i thought i had implied that lol. i completely agree that keeping small ones is what we should be doing. thats what i meant to imply when i said we need to get the ones with the bad (small) genes out of the gene pool. i just was trying to make the point that strictly catch and release is not the answer.

[Burnham]

Originally Posted By: Big E

+1

This has been studied and proven definitively. Keeping larger male bluegill is the key reason for stunting. If you keep the larger males, the smaller males sexually mature more quickly to fill the void, and divert energy into reproducing rather than growing. I can dig up the studies and post here if people are interested.

It's hard for folks to swallow... but keep those fish 7-8". Let those fish 9" and bigger go. Nothing wrong with doing that - in fact, it should be applauded, not looked down upon for keeping "small" fish.

+3

[solbes]

It's hard to convince others of this. The lake we fish 90% of the time has tons of bluegills. But I've personally only seen 3 over 9". Luckily all three were returned. Took very little to convince my daughter to let the big one go, but took a lot more to convince my brother in law. He did though, and we still keep plenty in the the 6-7" range if we are looking for some work and a meal.

[upnorthozzy]

Amen! Should be 5 fish limit from May 1st till July 1st.

[duckhuntr21]

It's hard to convince others of this. The lake we fish 90% of the time has tons of bluegills. But I've personally only seen 3 over 9". Luckily all three were returned. Took very little to convince my daughter to let the big one go, but took a lot more to convince my brother in law. He did though, and we still keep plenty in the the 6-7" range if we are looking for some work and a meal.

This is the same way with my dad and friends. They have no problems accepting that large pike, bass, and walleyes need to be protected for spawning but for some reason sunfish and crappies are different.

[Ctrl_Alt_Dlt]

Good to know!