Do you love big bluegill?
Why Everything You Know About Bluegill Management is Wrong
BY MATT MILLER
OCTOBER 15, 2015
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.
Researcher Andre Rypel (right) first encountered bluegills as many of us do: as a young kid, fishing.
“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.”
TAGS: Field Notes, Fish, Fisheries, Nature + People, NaturePop, Weird Nature
Matt Miller is director of science communications for The Nature Conservancy and editor of the Cool Green Science blog. A lifelong naturalist and outdoor enthusiast, he has covered stories on science and nature around the globe. Matt has worked for the Conservancy for the past 14 years, previously serving as director of communications for the Idaho program. More from Matt
Thanks, Slip. Now it makes a little more sense.
Makes sense to me and glad I read it. For years I took and cleaned alot of fish. Now that idea has passed for two reasons. First off I can't stand still in one spot that long to clean hundreds of fish . Second reason is after my partners and I fished a certain lake to long it seemed liked the gills were getting smaller. The explanation above explains that now . Course I haven't been to the old lakes in Iowa I fished years ago and may have to go back this year to see if they have recovered yet or not....Thanks for the post .....
YW Tootie…I never really 100% understood it either… im old school like you fished for many years… we were always taught or heard that you could never hurt a B’Gill population… it would always be replenished … but now the numbers are in from actual studies it makes you think.
Here is another result from a study done in Missouri… and by the way another good article pertaining to B’Gill conservation.
"The tagging study has shown that anglers can harvest a high percentage of the largest fish. Also , many of the large bluegills can be harvested by a small number of skilled anglers, even a fairly large impoundment."
Darn!.... looked up on the North American Journal of Fisheries Management for the results of the study... article was written and published but they wanted $25.00 dollars for the .pdf
only thing I can say is;; Tony has shown us some huge; great quality blue gills he has grown;; along with Bruce Condellos; and Walt Foreman;; these guys are definitly doing something right !
definitely alot of enthusiam and study behind it all
I'm learning a lot. This is a great discussion. Also read Tony's post and link, below:
Maybe if more didn't fish spawning beds for the bigger males we'd have a lot bigger bluegills? Is that the the bottom line?
Not necessarily....unfortunately there are no hard and fast guarantees. Yes, harvest strategy can impact the size structure of a given BOW, but there are other variables in play there also. That's the trick, in that no two bodies of water are the same.
However, it is generally recognized these days that the largest size class of male bluegills present in a pond or lake do play a pivotal role in determining the hierarchy. And here at BBG, we do advocate for releasing the largest size class of males. It can't hurt, and it may in fact help a great deal. Harvest some of the smaller fish, and release the biggest.
this has been known science from at least as far back as the 80s.the internet has been the final nail in the coffin for many fisheries.i cant believe how many people have to brag about their catch and then put all the the whare and when on the internet.a lake i visit every year was known for large gills.every one is now complaining about the small gills .they have no idea they caused this problem..this is just over the last decade.have no idea why someone keeps 100 bluegills.especially big males.i dont even fish for gills on this lake anymore.i do fish for crappies and they have a strict limit and are doing fine.
Ok , let's stir this up a bit, not one management style will work for all bodies of water, too many variations, Northern Growing Season vs Southern growing season ,Small bodies of water vs larger bodies of water, ponds and lakes vs rivers and streams , lots of harvest pressure vs little harvest pressure, trophy fishing vs meat fishing , carrying capacity of a body of water , supplemental feeding programs or let Mother Nature be in control, this is just way too variables for just one method of management to cover all situations and this isn't even bringing up the subject of catch and release mortality.
Trophy hunters need to bite the bullet and cough up the cash to produce their own pond and control the population of the bass to bluegill ratio, control the feeding program , and control the fishing pressure to guarantee that they will have trophy fish every time they go fishing, you know , just like Richman Mills.
Meat hunters are going after quantity, and they don't care about management style, just fish in the boat , I guess you could call them uneducated fishermen and they would call you names too.
My personal management style depends on the body of water I'm on, yes I care about the size of fish I catch and catching big fish is more fun than catching little fish, and I do not want to destroy the resource but on the other hand you have got to remember that this is a renewable resource. I raise trees at my farm and the big trophy trees are the mature trees and those are the ones that are ones that are at the end of their life cycle and therefor they are the ones that need harvesting, I dont practice catch and release on those trees , I don't try to prop them up after I cut them down, and I realize that by removing them they offer more sunlight for others to grow and mature, and I sure don't target the medium size trees to harvest because they will never become Trophy Trees. If you let the old trees die and rot and you don't let the medium size trees mature you never will have Trophy Trees , all you will have left is smaller trees.
Maybe fisherman should look at harvest like a scientific sample of the population, keeping everything caught up to the legal limit or their own personal limit no matter what size . If you catch a lot of little ones that limits the amount of more mature fish you can put in your creel,,this means no catch and release and therefor no catch and release mortality to deal with . This technique should allow the more abundant smaller fish to be removed and protect a portion of the more mature fish to survive. This might have to change the Trophy Fisherman's Style but this should provide more Trophy Fish and the only thing that would make it an even better Trophy is if it was a Free Range Trophy ! LOFR