Some lakes will experience year classes of stunted sunfish, and sometimes the effects seem to be irreversible. So just how do Northern areas compare to Southern areas when looking to land a trophy sunfish.
Many lakes that once produced big sunfish might now find themselves falling short because of over harvesting, biological factors, or environmental factors, especially in the smaller lakes. The larger Northern lakes seem to withstand some of the negative variables that are thrown at them; however, larger lakes also need attention in order to preserve the trophy fish. So, with that being said, if you can pinpoint those big sunfish on larger Northern MN lakes your chance of hooking into a trophy is there.
Southern Minnesota lakes, in some areas, are a little more fertile than the Northern lakes and can grow larger sunfish at a faster rate. Many of the field or "farm" ponds/lakes of Southern Minnesota hold some monster sunfish that will push the 1-pound mark. Certain characteristics allow for these fish to grow fast, but I wouldn't go as far to say they are in a totally different league than the Northern lakes. The lakes even further South (like South Carolina, Nebraska, Missouri, etc) experience much warmer temps all year round, allowing the fish to grow exceedingly fast compared to the Northern lakes (which includes all of Minnesota).
Expect to find more seven year-old sunfish in the Northern states than in the Southern states. A three year-old sunfish down South is typically larger than a three year-old sunfish up in Minnesota, same with crappies. Not a whole lot of crappies live to be ten years old down in Florida, Louisiana, etc, but you will see many (relatively speaking) ten year-old crappies in Minnesota, across both the Northern belt and the Southern belt. Fish grow slower in Northern areas, as a general rule, and the Southern U.S. fish don't experience as much of a metabolic slow-down like the fish experience up here during the winter months.
Water temps and activity levels down South will remain much higher on average than up in Minnesota. The diet of a panfish down South is also meatier and more frequent. Many Northern panfish feed heavily on plankton, zooplankton and other micro-organisms, where down South you see a lot of scuds, minnows, crawdads, larger insects, etc, devoured on a more regular basis. Sure, Southern state panfish still eat their fair share of micro-organisms, but they also snap up a lot more larger morsels as well, and on a more consistent basis. Same goes for Northern state panfish, where they also eat their fair share of minnows and larger forage items, but not on a twelve-month regimen.
Now, when comparing Northern Minnesota to Southern Minnesota you won't see as drastic of a change as you would by comparing Minnesota with Southern U.S. lakes. I do believe that some of the Southern Minnesota lakes have a better potential of producing larger sunfish on a consistent basis and more rapidly than Northern Minnesota lakes. However, many of the Northern Minnesota lakes are larger than the Southern Minnesota lakes and can produce higher populations of these big fish, and they also have more places to hide. Grow is slower up North, but so is the death-rate. Southern lakes tend to produce strong year classes of big fish and they grow fast, but the numbers sometimes tend to be less than that of the Northern lakes.
It all comes down to the lake type, forage and surroundings (with a dash of geographical location) when developing trophy sunfish. Some lakes just won't see a good population of large Sunfish, and some lakes might have at one time seen large fish, but because of a change in conditions, might experience a prominent decrease in larger fish.
I personally like to target large sunfish in moving water systems or lake chains. These are bodies of water where water is coming in and moving out, which can produce some monster sunfish, even if the average depth is shallow. A constant flow of high oxygen, no matter the season, is a contributing factor to a sunfish's quality of life. You also have more oxygen for vegetation, forage and other surroundings that allow for a healthy panfish population and growth rate.
The winter months also don’t affect these moving systems so hard, and the strain on these bodies of water is less drastic. Having an "upstream" and "downstream" also aids in the spawning process, especially when these channels connect to several different lakes or bodies of water. Shallow pools/bays along current areas will hold fish in slack water during the spawn given the right conditions. I also like these types of systems because sunfish have more options for hiding and places to devour food, making it tougher to catch the brutes, which in turn can mean a better population of larger fish.
Larger current systems can oftentimes stump even the most prolific of anglers when trying to locate big panfish, myself included. However, I believe there is nothing wrong with that. This ensures that when you do find the big fish, you find more than one and there are less flukes. Big fish will use similar areas at like times, and you can pattern these fish, even on large current systems/chains where several lakes join. A very important thing to remember though is to practice catch and release on those larger fish, as they’ve been through a lengthy process to reach that point and they should be considered trophy fish.
So, to the topic of Southern Minnesota lakes versus Northern Minnesota lakes... I think your chances are good in both areas for catching large sunfish. It can really be a timing thing though. Southern lakes will warm up faster, because they are not only further south, but they typically have more stained water with darker bottoms, and you might experience a better early season bite. Northern lakes typically have excellent late-spring and summer bites for large sunfish.
If I was going to target just big sunfish during the summer months, I would hit the Northern lakes. Water temps seem to keep the bigger fish in schools and in more generalized areas, where the Southern lakes will experience a more scattered, warm water effect. Larger sunfish might push deep or hug to the bottom in the weeds during the hot summer months on Southern lakes, where you can find larger sunfish along deeper weed lines and breaks in the Northern lakes.
I'm sure you could argue this either way, and I'm sure some people would prefer Northern Minnesota lakes over Southern Minnesota lakes and visa versa. Both areas will, and do, hold large sunfish and the potential of catching a 1-pound sunfish is definitely there.
Sunfish are an excellent species to utilize when taking a kid out on the water. They provide constant action and are a lot of fun to catch. Landing a trophy sunfish should be considered an accomplishment, and is definitely something to cherish!!!