Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations 14 ounce bluegill (not hybrid) only 9 inches!

Not bragging at all but I wanted to share this with other bluegill afficionados. I was delighted to catch and release a 14 ounce bluegill (weighed on my butcher/produce scale so it is accurate) out of one of my ponds yesterday. (My bluegills aren't hybrids.) Hopefully in another year there will be one pounders and over.

I almost didn't get him in as he tried to wrap the line around one of the pier posts. Isn't it funny how the bigger fish seem to know these tricks? I had to submerge the fly rod and reel, and pull it around the post to get this devil in. This is one of the stockiest northern bluegill I have seen. Of course the camera didn't have film, and I had access to a digital camera a day before, but the wife took it back to school.

I believe this bluegill is one of about 100 feed trained bluegills I put in the pond a couple of years ago that were about 7 inches then. The body configuration on these is very rounded. I got them from a Mike Robinson of Keystone Hatchery in northern Illinois. He says the brookstock came from Wisconsin.

I'm managing the pond by thinning out the smaller bluegills (under 8 inches) and releasing the big ones until they weigh a pound and over 10 inches. Average size in the pond is around 7 1/2 inches.

I have lot of bass in the pond to keep the bluegill numbers down in which the population is composed of pond reproduced bass (not feed trained and slower growing), and much larger faster growing feed trained bass that I plant annually.

Cecil

Great work Cecil, how close did you say you were from that nucleur plant to raise these size native northern bluegill. HA!HA!
I can only wish to get them that size?

Rowly

Cecil:
Take a photo! Send it here, so I can post it and we can all share your accomplishment.
Mark McDonald

I'll get some film for the camera and have it ready this time. 14 ounces pretty heavy for a 9 inch bluegill?

Cecil

Fishery biologists often monitor fish condition (plumpness), and one of the common tools we use is termed "relative weight." A relative weight of 100 indicates a fish in good condition. Well, a 9-inch bluegill that weighs 0.62 pounds is in good condition. So, if your 9-inch bluegill weighed 14 ounces (0.875 lb), then it had a relative weight value of 141. That is a truly impressive fish. One place where I have consistently seen wild bluegills in such has condition has been in some of the Nebraska Sandhill lakes. Those lakes are shallow, with much plant growth, and the amount of insects produced is amazing. Bluegills there must agree, but we do see some fish with relative weight values as high as 140. Nothing matches those big bluegills!!

Dave,

I've seen those bluegills too as being a fish taxidermist I've mounted a few caught out of Pelican Lake, Nebraska. These were at least 10 inch bluegills and they look like they are on steroids. One was reportedly over 2 pounds although I didn't weight it. Have you seen all the one pound and bigger bluegills listed on Nebraskas Fish & Game site that came out of Pelican Lake? The list goes on and on.

I talked to a biologist from Nebraska and asked why they are so big. He said they are studying them and aren't entirely sure, but the food supply is a big part of it as you said. I've been told Pelican Lake is about 800 acres and is so rich in food that it becomes weed choked in summer, and even has partial winter kills some years. The biologist said all you have to do is pull up some weeds, and you will have a lot of insects clinging to the weeds and some of the insects are quite large.

What interested me is a weed choked lake that grows big bluegills is an anomaly. Typically the weeds keep too many bluegills from being thinned by predators and the size goes down. Maybe the incredible food supply available and the sporadic winter kills keep the numbers down, and there are other factors.

I do believe (and its common sense) if a fish gets a head start early on growth by an ample food supply they may ultimately be bigger later when all is said and done. The bluegill that I caught along with others originally came from a hatchery, and was feed trained and was already 7 inches in length at only 2 years of age. Now that it is feeding in a fertile pond with little competition, (I have lots of bass and predator fish to keep bluegill reproduction down) having a head start on the feed, it is doing quite well. I also periodically thin out bluegills under 8 inches and have noted their entire GI tract is packed with food so apparently there is ample natural feed.

I still can't wait to take males from this pond, get them conditioned on feed in a floating cage as Bill Cody does, and then transfer them to a smaller pond where I can exclusively feed them on floating feed along with female only feed trained perch. It should be an interesting and fun experiment. No reproduction to increase competition, and no predator fish to intimidate panfish at feeding time. Right now most of the bluegills in the pond the 14 ouncer came from are intimidated by the largemouths at feeding time and have reverted to natural feed.

Cecil

Fish Growth. Quoting Cecil's 09 Sept comment "I do believe (and its common sense) that if a fish gets a head start early on growth by an ample food supply they may ultimately be bigger later when all is said and done". Discussion of this concept follows:
Fact. Once fish are stunted they can resume growth when the food supply again becomes adequate for growth. It was thought and rumored that the stunted fish, when given unlimited food, would double their growth and/or catch up with the growth that was lost during stunting. I've researched this and found this phenomonon not to be true; at least in the stunted fish I've tested and papers I've read. Univ of Missouri is working on this stunting-regrowth character (see my Sept 09 post titled Bigger Bluegills). But research I've read concludes a food deprived fish is quite different than a stunted fish. When a fish is stunted (at least by my definition) its eyes keep growing and get disproportionate to the head. Now this fish is stunted which would take at least one season not a week or two as in the food deprived fish in the Univ. Missouri study.

Key here is the length of time that the fish is starved or stunted before growth is resumed. Too long of a stunting period and the fish cannot catch up to its siblings who have never lost any feeding time or growth. These stunted fish can resume growth BUT, assuming they both have the same life span, the stunted ones will never catch up to their siblings who have maintained maximum growth their entire life.

However---

Research and data indicate that fish that grow at the maximum rate tend to have shorter life spans i.e. southern bass vs. northern bass. What if the stunted fish lives longer than the fast growing siblings? Then the stunted fish's final size could possibly be the same or larger than the fast growth sibling. Next we need to find out: What part does annual temperature play in fish growth and a fish's life span assuming food is not a limiting factor?

For Cecil: I have had the pleasure of both working and fishing on Pelican Lake. The Nebraska Game and Parks Commission fisheries chief is Don Gabelhouse, and he's a bluegill "nut." Thus, it's great fun to work and play down there.

Most of those big bluegills come out of Pelican Lake during ice fishing season. There is some, but not much, fishing during the open-water season. Most people that know of these lakes, but haven't been there, think that they are covered with vegetation. However, it is a little more complicated than that. The vegetation, both submergent and emergent, is scattered throughout the lake. So, there are open-water areas both near-shore and off-shore. Perhaps I should just call it "patchy." When we sampled the vegetation there (Pelican) in 1998, the emergent vegetation (cattails and bulrushes) covered about 14% of the lake area, and the submergents (pondweed, milfoil, coontail) covered about 22%. So, even though the lake is "covered" with vegetation, it is not as dense as you might think. In a study of 30 of those Sandhill lakes, the higher quality bluegills still occurred in lakes with higher abundance of largemouth bass. I think the patchy nature of the vegetation lets the bass thin the small bluegills. Then, the bluegills grow like gangbusters on all those insects. Based on our growth analysis, the Pelican Lake bluegills reach 10 inches (over a pound) at age 7, on average.

Bill: I certainly believe you are correct about the stunted fish. If they are moved to a setting where they have plenty of food per individual, then they will indeed increase growth. However, some of their "opportunity" has been lost, and they'll never reach their potential. Their first offspring will outgrow them, assuming conditions stay correct for fast growth.

You are also right about the "faster growth often leads to higher natural mortality and shorter life span" for many fishes. That's part of the reason that crappie minimum length limits have not always worked around the country. In some waters, they grow fast and die you, and protecting them with a length limit just lets them die of natural causes without being harvested. In waters with more moderate growth rate, they live longer, and sometimes the regulation is more effective. It comes right back to the idea of water by water management. We've seen the same problems with some yellow perch populations in South Dakota. In the fast-growing populations (12-13 inches at age 5), they fish often do not live more than 5 years. In the slow-growing populations, they commonly live more longer lives.

In most cases, I think we'll find a "dome-shaped" relationship between fish growth and temperature. Both too hot and too cool can cause slower growth. For some fishes, too hot can also mean no survival. I've often wondered if that is the reason that yellow perch do not survive in very many places in Kansas. Too warm.

Well, I hope I wasn't lecturing too much. You guys just asked some interesting questions, and I could resist.

David Willis,
What is "water by water management"?

Actually, that was my "short-hand" waying of mentioning a tough problem that faces the fisheries profession. Biologically, we really need to assess habitat and fish communities on a water by water basis, and then make the right decision for that water. For example, perhaps largemouth bass might best be managed with a minimum length limit on one lake, a protected slot regulation on a second lake, and no limit is warranted on a third lake. Each lake has unique characteristics, and biologists would like to manage them as individuals.

The controversy part comes up because we are all sensititve to the issue of too much regulation/too complex regulations. Many biologists worry that we might even limit the number of new people who want to join the ranks of anglers by making things too complex. Adminstrators in most state agencies are always hoping to find ways to simplify regulations. It's an admirable goal, but often makes the "water by water" management a little more difficult to accomplish.

Hope that's not "too much information!"

Dave,

There is never too much information and discussion on growing big fish -- at least in my opinion. Keep it coming!

I do believe genetics come in to play also don't you? If I wanted to grow big bluegills I would in the least want a stock that has proven to grow large under similar conditions.

Interesting about the fast growth/earlier mortality idea. When I did an outdoor column for a local newspaper I did some interviewing of biologists that were expecting the next world record brown trout to come out of Lake Michigan. They were, and still are, planting a strain known as the Seeforellen strain originally from large lakes in Bavaria and had high hopes for this strain. However one biologist had reservations as he felt they may not live long enough due to the fast growth and warmer water in Lake Michigan (relatively speaking). However they are finding they are not dying out in the 30 pound range so there may be a new world record after all.

I'm hoping our cool down in the fall and winter up here in the north will preclude any early death, and even if the bluegills I planted from the Illinois hatchery peak at 5 or 6 years that means the 14 ouncers still have two years to go.

Cecil

Boy, Cecil, you put me on the spot with that genetics question!

To be honest, I'm not a great big fan of genetics explaining a lot of what happens in fisheries management. Having said that, my rear end is really hanging out if any genetics folks read this!!

Here's my general thought. Just take a stunted bluegill population as an example. They aren't stunted because of poor genetics. They most often are stunted because there are too many individuals for the available food supply. If you move them to a good environmental situation, they typically grow well, and their offspring do even better.

Having said that, there certainly are unique genetic circumstances that occur out there, but most often they involve unique genetics strains, etc. Your brown trout example, which I had not previously heard about, could certainly be one example. Another that jumps right to mind is that Shoepack strain of muskies that has such a smaller maximum size than most other muskies.

We wondered if there was anything unique about the Pelican Lake bluegills, and I had actually talked to one of our premiere fish geneticists (Dave Philipp of the Illinois Natural History Survey) about assessing some samples, but that did fall through the cracks. Some Sandhill lakes produce mostly 8 and 9 inch bluegills (nice fish, but not monsters!), while others such as Pelican produce those honest, 10-12 inch, 1 pound and even 2 pound, bluegills. I suspect the genetic material is similar between lakes, as bluegills are moved around after winterkills, etc. In fact, there is a big year class of bluegills in Pelican Lake right now that are about 9-10 inches right now, and it just so happens that that there was a big stocking of bluegills from the Valentine state hatchery the year that those fish were hatched. Normally, we don't think of supplementally stocking bluegills. However, if those fish are primarily from the hatchery, then they are growing like gangbusters, and that points more to the food supply in a good living environment than to genetics?

Anyway, how's that answer for "riding the fence?"

Dave

Good answer but I would still feel safer with a proven strain of fish that can reach large size, and then feeding then well and raising them in an ideal environment.

A possible example is an experience I had with smallmouth recently. I have a pond with two different age classes of smallmouth. One group from northern Illinois (I'm in northern Indiana)I got two years ago did great from the get go with fast growth and good condition factors and they are even doing well competeing with largemouth bass. This year I got another group from another state that aren't growing fast and are pretty whimpy. They just don't seem to be adapting to my pond while the other group from closer to home are doing well. I know there could be other factors, but the first group I believe is better adapted genitically than the second group. Possibly similar water chemistry etc. (The second group came from New York).

Good point. I certainly do believe that locally adapted fish would be superior.

Cecil - About your SMB from NY not growing very well, when you get fish from a hactchery like that you should try and insure that what you get are not culls or runts where the larger fish were previously graded out. It doesn't happen a lot but it does occur. A lot of things could explain why they are not growing as well as your northern IL SMB. Don't be too quick to blame it on genetics which it could be.

Bill,

Actually wasn't blaming it on genetic factors as I did say there could be other factors. But I do believe genetics play a role.

Have you received any emails from me in the last month? I've sent them to you but there was no response. Maybe there is something wrong with one of our servers again.