stunted growth in panfish

[hunter322]

I was fishing a smaller lake the other day and all we were catching were these dinky sunnys and crappies. I got to wondering, what causes stunted fish growth? Is it poor water quality? Is it not enough food? Is it overcrowding? Is there anything i can look for when im deciding on a certain body of water to fish?

[TravP]

Overharvest of the bigger males is the #1 problem IMO. They carry the genes.

[blackdog1101]

It's it possible that your small lake suffered from winter kill, or some sort of low oxygen situation during the summer?

[hunter322]

i doubt it cause the lake is 26' deep. its only 68 acres to. im just wondering in general for all lakes is there anything one would look for?

[Nick Kuhn]

Overharvest of the bigger fish is almost always the cause. In lakes that lack food or habitat, you simply find that the sunfish populations are very low.

[Jim Uran]

I agree, a small lake like that must have been pounded and probably still gets pounded. Taking out the big males is always detrimental to a panfish lake.

[Chad Peterson]

+1 and +2. Need to be more selective on the fish. This happens all the time and the one thing that I hear all the time........."What happened to the fish?" Be selective!

[smallie_hawgin]

I was fishing a smaller lake the other day and all we were catching were these dinky sunnys and crappies. I got to wondering, what causes stunted fish growth? Is it poor water quality? Is it not enough food? Is it overcrowding? Is there anything i can look for when im deciding on a certain body of water to fish?

As has been mentioned by others, the largest males in the population do actually control what the largest size individuals in the given lake can attain. It is actually related to the spawning hierarchy and the overall size at sexual maturity. This is one of the reasons that a simple reduced bag limit can be effective in lakes that have adequate growth for sunfish.

That said, the habitat which is highly correlated with the overall food availability, definitely makes a difference. Most lakes in MN are capable of producing larger sunfish than the run of the mill 6" male. Fishing pressure does exert quite a force especially on smaller lakes like the one you mentioned. We often see boom and bust (more likely a significant year class of fish moving through that attain a larger size)fisheries that become popular to anglers and the lake gets hit by many in the area.

This is where reduced bag limits have the ability to distribute the harvest a little more uniformly and allow some larger individuals to stay in the population; therefor maintaining the larger size at maturity.

The lakes that can debunk this are typical winterkill scenarios (IE-Pelican Lake near St. Michael). These lakes often are very nutrient rich and have lower density populations that grow incredibly fast because of extreme food availability. The way our winters are going as of late, this may be a less frequent scenario than in the "old days", however, it still does happen.

Just a few cents worth...

[Wes Ellis]

I know a lake back in the woods a little over 1 mile. Every time I have fished it and that hac been since 1963, The bigger crappies are 9" and skinny the biggest sunfish 7"(that I have cought) Was told last winter some one got some 12" crappies? They are stacked in the lake. nice northerns and largemouth bass. There dont seem to be any minnows in the lake? The crick coming out nevere has minnows. Very few fish the lake how ever it does get fished in the winter more than summer because of the swamps you have to cross to get there.

[Spike76]

In my years of fishing, I've noticed every big fish started out a fish egg and grew. The fish are small before they are big. Some days the fish don't bite and some days only small skinny ones bite. Change your bait and move around. Some lakes might have more small fish but the genes in the fish were passed on from the fish that are in the lake. If there were big fish in a lake, there will be big fish in that lake. I don't believe there is stunted growth from over harvest of the big ones. They should do better because the big fish won't be eating all the food. If a fish has a poor diet it will probably be stunted. The genes in them will be the same. Just my opinion from about 60 years of fishing.

[Mattbrome]

I had a similar question so I hit up a friend of mine at the DNR. Here is my email to him, and his answer. I don't know how to upload a PDF file here, but if anyone is interested, he also sent me a report about Crappie and Bluegill exploitation by anglers. It talks about stunted growth and what affects the size structure if these fish in our lakes. Very interesting reading. Email me and I'll send you the report. [email protected]

My original email:

Hello Tim-

Again, thank you in advance for your thoughtful comments on another question of mine concerning fisheries in Minnesota.

What suggestions can the DNR give us on how to maintain or better yet, improve our favorite lakes through selective harvest? What size of fish, in inches, should be considered an acceptable size to keep if we are practicing selective harvest? Species I am particularly interested in are black crappie, bluegill, walleye, and pike.

Secondly, when considering frequency of harvest, how often is ethically suggested for keeping a limit of fish? I understand that as a license holding angler, I am allowed to keep fish whenever I like as long as I am within the combined bag limit both on the lake and in possession at home, but am looking for your insight. For example, how often is ethical to take a limit of crappies from a lake? What about the other species I have mentioned?

Thank you for taking the time to answer my inquires. Looking forward to your reply.

-Matt

Tim's Response:

Hi Matt,

My suggestion would be to view this link to the DNR HSOforum. http://www.dnr.state.mn.us/fisheries/management/regs.html This link should answer most of your questions.

As noted in the MN fishing regs most of the selective harvest is done for walleye anglers as only one fish over 20” is allowed in the bag, and then there are the various regs particular to many walleye waters with the various slot limits in place to keep walleye fishing great in MN. For Pike the same story is true with no more than 1 pike over 30” allowed in the bag except on certain lakes where protected slots are in place to improve overall pike size structure (to have more larger pike and less snakes). For panfish the problem is really complex, most anglers wouldn’t want the remedy needed to improve bluegill fishing (catching bigger bluegills 8”-10” or larger) The bag would need to be reduced to something like 5 fish in possession. DNR angler survey results indicate that most anglers would not be in favor of such a restrictive bag limit for bluegill or crappie. It takes a long time to grow a large bluegill or crappie in most of MN, like 6-10 yrs.

As for ethics, that is for each angler to determine for themselves. The daily bag and possession limit are the same thing in MN, the days of loading the freezer for the neighborhood fish fry are over. For me ethically, what I keep are smaller fish and usually no more than enough for a meal. My wife and I have 4 children but we don’t take limits for 6 people, just enough for a meal for the family. Actually we really never get anywhere near a limit for all us anyway. Attached is a paper that should help in your quest for answers.

Tim Ohmann

Fisheries Specialist

[hunter322]

Thanks for the reply matt and welcome to HSO!

[Mattbrome]

Thanks for the reply matt and welcome to HSO!

You're very welcome. If anyone else wants the report, feel free to let me know.

[frazwood]

If it is true the size of the large males determines the potential size of the whole lake, then would it makes sense to:

Keep as many fish as you want, just make sure not to keep the LARGEST size fish in the lake. That is, if the lake has a few 9 inch 'gills, don't keep anything over 8 inches. Or, if the lake has a few 8 inch 'gills, don't keep anything over 7 inches.

Me? If I am fishing a lake with a lot of nice 'gills, I tend to be the local "nut", as I throw back the big ones and keep the small ones. Otherwise, I tend to go to the lakes with a lot of small bluegills and keep a bunch of them. No one seems to care if I keep a limit of 6 inch bluegills and they're as tasty as anything I catch.

[hunter322]

And how do you tell the sex in fish?

[Scott M]

Try these comparisons for bluegills. There are more pronounced differences in other fish species. The best way is internal gamete comparison, but that would mean killing the fish

[GSP4ME]

we're you out on fawn sure sounds like it

[Tom7227]

On the smaller lakes that were mentioned in this post maybe one problem is the lack of food. A body of water can only produce X amount of biomass. Lots of things go into creating the limit - chemistry of the water, water clarity, composition of the bottom, whether there are inlets and what comes in via them ....

If you end up overpopulating a body of water with fish then things get out of whack. Not enough zooplankton to feed the small baitfish and panfish, not enough panfish to feed the larger predators like bass, walleye and pike. I believe that you can end up with stunted fish just because things are out of whack and there isn't enough for everyone to eat.

Steve McComas, the Lake Doctor, wrote a book about fresh water biology. You may be able to get a copy of it at your local library. It is a great resource. Additional information is available here - http://www.dnr.state.mn.us/publications/fisheries/investigational_reports.html

[SmellEsox]

In my years of fishing, I've noticed every big fish started out a fish egg and grew. The fish are small before they are big. Some days the fish don't bite and some days only small skinny ones bite. Change your bait and move around. Some lakes might have more small fish but the genes in the fish were passed on from the fish that are in the lake. If there were big fish in a lake, there will be big fish in that lake. I don't believe there is stunted growth from over harvest of the big ones. They should do better because the big fish won't be eating all the food. If a fish has a poor diet it will probably be stunted. The genes in them will be the same. Just my opinion from about 60 years of fishing.

In just about every bluegill population, there is a genetic component made up of males called cuckolders that mature early at a very small size. When parental males are overharvested, this genetic trait (cuckoldery) can theoretically become more prevalent in the lake leading to a decline in the ultimate size of bluegill in the population. Some lakes in MN with high angling pressure were found to have a higher percentage of these fish in the population. However, some other high pressure lakes didn't have that problem. So it appears that this shift in genetics can occur in some lakes possibly due to fishing pressure.

Some lakes just don't appear to be able to produce big sunfish due to a lack of productivity. There are many fairly pristine lakes in the Little Falls area that have excellent water quality but have poor bluegill size structure. I've aged a ton of bluegill from these lakes and they grow very slowly. In our best bluegill lakes a fish can reach keeper size (7") in 4 years. On some of these poor lakes, it takes a fish 8-10 years to get that big, and when they do, there condition is no where near as good as those seen from "good" bluegill lakes (read, they are skinny). I guess the message here is that not all lakes have the capability of producing high numbers of large sunfish.