Bluegills are prone to overpopulation. This is accepted knowledge among many anglers.
If you don’t catch and keep a lot of bluegills out of a pond, you’ll often hear a fisherman say, the bluegills will overrun the place. You’ll soon have a pond full of runty, stunted fish.
This is why the bag limits for bluegills are typically very liberal – it is not unusual to be able to keep 25 fish a day. It’s the angler’s duty to catch and eat as many as possible – keep the herd in check, if you will.
It sounds good, but current research suggests it’s wrong.
In fact, research conducted by Andrew Rypel, research biologist with the Wisconsin Department of Natural Resources, suggests the opposite: that liberal harvest limits on bluegills actually decreases the size of fish.
“Fish Here Aren’t As Big As They Used to Be”
Bluegills are often the first fish many anglers encounter (including me). They are common in farm and urban ponds. They’re the fish kids catch with a Mickey Mouse rod, a bobber and worms.
In the spring, many anglers target them on their spawning beds, where the biggest males are often easy to catch (see yesterday’s blog for the full details on this spectacle).
Bluegills are also popular because they’re tasty. Anglers call them and similar-sized species – crappies, perch, other sunfish – panfish. They’re the perfect size to fit in a frying pan.
Rypel and his colleagues in Wisconsin noticed something over the years: Anglers reported decreasing size of bluegills and other panfish. Of course, conventional angling wisdom would suggest the solution to this would be to harvest even more bluegills. After all, decreasing size is a sign of overpopulation.
Research tells a different story.
Rypel analyzed size trends going back to the 1940’s, and found that bluegills (and other panfish species) steadily declined in size over a 70-year period.
“The regulations are relatively liberal,” he says. “I thought one possibility might be that we were fishing them too hard. As we looked at the data, we found that evidence of bluegills becoming stunted because they were overpopulated was not as common as previously thought.”
Fishing pressure, particularly on spawning beds where bluegills are most vulnerable, can be intense. And that pressure may be decreasing the size of fish.
In response to the trend, the Wisconsin DNR reduced the bag limit to 10 fish on 10 lakes as a test. Researchers, including Rypel, analyzed fish size before and after the regulation.
They found that fish size increased on average a half-inch on maximum size and .8 inch on mean size.
That may not sound like much, but consider that a typical bluegill is six or seven inches, and a really large one is ten inches.
Rypel published the findings in the North American Journal of Fisheries Management.
A New Experiment in Bluegill Management
The next phase of the project is to implement new management strategies on 100 Wisconsin lakes. One third will have a reduced limit of 10, one third will have a reduced limit of 5, and one third will have a reduced bag limit only during the spawning season.
The management regimes will run for ten years. “We’re going to find out what different regulations can do for panfish size,” says Rypel.
The good news is that bluegill size rebounds when fishing pressure decreases. A study by Rypel in collaboration with researchers at the University of Wisconsin-Milwaukee, School of Freshwater Sciences found that the reduction in size was not likely due to a shift in genetics, as has been shown to be the case in some other prominent studies on fishing pressure.
Anglers have, in general, been reluctant to embrace size limit reductions. Rypel points out that the limit reductions may actually result in more meat harvested. That may seem counterintuitive, but it’s true. “As bluegills get bigger in length, they get exponentially bigger in weight,” he says. “So if you catch a few larger bluegills, you often get more meat than if you caught a bunch of smaller ones.”
There is still a lot biologists don’t know about bluegills. New research will likely call for more changes in fishing regulation, but Rypel acknowledges that science is only one part of fisheries regulation.
“Regulations are a blunt instrument,” he says. “They cannot account for all aspects of fisheries management. If they get too complicated, they become much more difficult to enforce. We want regulations that are easy to understand and easy to enforce. There are trade-offs. In this case, reducing the bag limit could help the resource tremendously while still meeting the expectations of anglers.”
And while the bluegill may seem an unlikely symbol for global fisheries management, what Rypel says applies to large commercial fisheries as surely as it does the local farm pond. Regulations are only ever partly about science, and they can never fully account for the complexity of a fishery.
The key for resource managers is to use sound science to create regulations that work best – for fish and for people.
“Bluegills have the opportunity to get bigger with a relatively minor shift in fishing regulations,” says Rypel. “Our research is providing the evidence that it benefits anglers, too. The findings seem counter-intuitive to many anglers, who have long believed that smaller bluegills was a sign of overpopulation. But perhaps our long-term studies can convince them that lower bag limits can mean better fishing, and bigger panfish fillets for the fish fry.”
do some fun facts on them
I am doing a school project on how we can protect the Bluegill… I have alot of information already, but does anyone have anything they think I should add, that isn’t on this website? Thanks so much!
There may be some truth in this. Other factors must also be considered. The amount of minnows in many lakes has changed with the planting of game fish at larger sizes and resulting more game fish in the water. This can correlate to the over fishing and cherry picking that anglers are being blamed for. Fish behavior can also affect how well they grow. When there is too much danger of being attacked by a game fish with teeth feeding can be considerably curtailed. Often the food supply for bluegills is like a pasture that is over grazed and lacks productivity. If bluegill are held to a small range by game fish that may happen. Also fish grow the best when they can eat freely, because for some reason individuals like to specialize in what they eat. Sometimes bluegills developed dense schooling behavior to deal with the fear of game fish, but this puts any odd fish in danger because game fish can keep his eye on an individual in an attack. This may make larger individuals a game fish mark. The level of game fish in lakes does come at a price when the preferred food of oily fish and minnows are gone. Many good bluegill lakes are greatly reduced by the unnatural population increase of game fish which can add even more fishing pressure to other great bluegill waters. Virtual no lakes are managed for only the bluegills. It is never mentioned how very large panfish eat very small panfish thinning there numbers, helping to control the over feeding of the immature food supply of larger bluegill. That is why cherry picking might not help overall sizes. I could go on but i have only touched the iceberg because it has so many variations of what can go wrong.
It has also been proven where there is the combination of Largemouth Bass and bluegill, the population of the gills are kept down and the fish have more food and get bigger. A larger limit of fish also will take more fish out of the lake to increase size of the remaining. If there is intense fishing pressure on a lake there will be less bluegills but the size will increase also. Restricting the season till after spawning is complete may increase the size also.
I thought it was common knowledge now what the dynamics behind this are. Maybe I should say, are speculated to be – who knows for sure. Simple really. There are two factors at work. Fish tend to grow a lot faster before reaching sexual maturity. Once old enough to spawn, they put energy into that process, rather than body growth. And may eat less as well since they are occupied with spawning much of the time. The second factor is once they reach sexual maturity, the rigors of spawning, and maybe just some biological time clock also, dictate they will soon die. So, the sooner a bluegill reaches sexual maturity, the sooner it’s growth will slow. And the shorter its life span.
Now take a lake with a certain amount of desirable spawning habitat. A population of 5 year old, 9 to 10 inch bluegills, that control the spawning activity. Remove 80 percent of them, and 4 year old fish begin to fill the vacuum. Nature, in its wisdom, has made younger fish mature at an earlier age. The dominance of the bigger 5-year olds had kept the 4-year olds fast-growning juvies, but are no longer around to do that. Now you have a lake full of 4-year old bluegills that have practically stopped growing. Pretty simple idea really. Is it true? I don’t know, but many biologists have bought into it.
Very disappointing to see so many comments like “common sense dictates more fish will mean smaller fish”. Only in a very simple system with limited food supply and not subject to the confounding factors nature throws our way all the time.
Your observations Greg are good ones I believe. I’ve read studies that have shown protecting the large male nest guarders and focusing the harvest on smaller bluegills has been effective in restoring size balance to stunted bluegill lakes. The large male bluegills have the quality genetics a lake needs passed on, and they are the superior nest guarders ( also making them easily caught). If released, he is back “on station” over his nest in about 2 seconds. If kept, his nest is raided immediately, he and his nest are lost. In a lake full of stunted bluegill, perhaps focusing the harvest on the many small fish and protecting the quality larger fish is the answer to restore bluegill size quality.
I’m 71 years old and have been an avid pan fisherman all my life. I am an avid fly fisher and have tied my own flies and poppers since I was 10. Like most pan fishers I used to release females during the spawn but slay the males, especially the big old bulls. Now that I have aged and enjoy watching the unique bluegill spawning ritual I realize the role the large males play in the spawn. I enjoy the battle for the nest spot and the ensuing actual egg laying firtalization process. The most important thing I learned was the minute dominate male was taken from the bed small gills, crayfish and other predator fish cleaned the contents of the bed out therefor a dead nest. Upon retirement my wife and I bought a lot on a 40 acre inaccessible northern Wisconsin lake, it’s substrate is sand and gravel but is covered with 4 to 6 inches of muck. I have cleaned up several spots close the dock area and the gills immediately took the area over and have spawned as much as 4 times during the spring and summer. What I’m doing seams very fullfiling and productive and I hope its the right thing to do. I often paddle my canoe around the perimiter of the lake and have found very few bluegill spawning sites. I welcome any constructive comments or suggestions on what I am doing.
Though well-intentioned, the DNR may have issue with you disturbing a lake bed if you did not get their permission.
Nothing like the scientifically uninformed journalist. A lot of claims were made and accepted without question. The experiment cited involves uncontrolled natural experimentation with a ton of uncontrolled variables – the variations in fishing on the various lakes, fish density, number taken, and those quoted size changes are nothing but estimates, error factor unknown. The experimentation period was far too short to allow for any conclusions, only suggestions for further research. No mention of effects of size limits as well as bag limits. These researchers have a lot of work to do and more carefull scientific actions, before they can say anything that will achieve even strong plausibility, much less solid facts. Simple common sense will tell you that if the number of blues exceeds the amount of food available, the fish are going to be smaller – what’s needed is information as to when food scarcity becomes an issue – feeding conditions change and setting cast iron bag limits makes little sense, it would seem. At least the researchers seem to understand that they are in an area of unknowns.
Very interesting article I have personally found that in relatively small body’s of water i fish say under 5 acres the percentage of ten inch or bigger bluegill goes way up if there are a lot of bass around the 2-3 lb range when compared to other ponds with a bass population that has 5-7 lb bass or bigger Just my two cents thanks
Name correction for previous submition on blue gills, and a post note: bass and bluegills inhabit the same space but even as a predator , bass will rarely eat a bluegill over 3 or 4 inches because of their spines, so counting on them to thin the “herd” isn’t always successful. Even bass are susceptible to “stunting”.
I fished a 4 acre pond with many 12 inch fish, eventually I decided to remove 25 -12 inch fish. The following year the 12 inch fish were now 14 inches. So size management will work if properly conducted. Granted what I did was not a controlled experiment but it gave me insight to size verses numbers! HK