Wisconsin Fishing Size Limits: Bag, Slot, and Sturgeon Rules

Wisconsin fishing size limits start with statewide minimums set by the Department of Natural Resources: walleye and sauger must be at least 15 inches, largemouth and smallmouth bass 14 inches, northern pike 32 inches, muskellunge 40 inches, trout 8 inches, and lake sturgeon 60 inches.¹ Those numbers are the baseline. Hundreds of individual lakes and rivers carry their own exceptions that override the defaults, so the specific waterbody you plan to fish decides what you can legally keep.

Statewide Minimum Length Limits

Wisconsin Administrative Code NR 20.20(73) sets the baseline that applies to every inland lake and stream unless a waterbody-specific rule says otherwise:

Walleye and sauger: 15 inches
Largemouth and smallmouth bass: 14 inches
Northern pike: 32 inches
Muskellunge: 40 inches
Trout: 8 inches
Lake sturgeon: 60 inches

Panfish species, including bluegill, crappie, pumpkinseed, and yellow perch, have no statewide minimum size.¹ You can keep them at any length unless the lake you’re fishing has imposed a local restriction. Game fish not listed in the statewide table also carry no default minimum.

The northern pike figure surprises people. If you fished Wisconsin years ago or came over from a neighboring state, you may be used to a lower number. The current statewide default is 32 inches, and keeping a pike that falls short is one of the more common citations wardens write.¹

Daily Bag and Possession Limits

Length tells you how big a fish must be. Bag limits tell you how many you can keep in a single day, counted midnight to midnight:

Walleye, sauger, and hybrids: 5 total
Largemouth and smallmouth bass: 5 total
Northern pike: 5 on waters north of U.S. Highway 10; 2 on waters south of it
Panfish (bluegill, pumpkinseed, yellow perch, crappie): 25 total

The possession limit is separate and equals twice the daily bag. While you’re on the water, on the bank, or in your boat, you cannot have more than one day’s bag for that waterbody on your person. The doubled possession figure covers fish you’ve already brought home and stored in a freezer, cooler, or vehicle from an earlier trip.³ If your daily bag for walleye is 5, you can never control more than 10 walleye at any time, no matter how many trips produced them.

Fishing more than one waterbody in the same day is allowed, and you can combine catches, so long as you never exceeded the daily limit on any single lake or river.³ Many specific lakes carry reduced bag limits that replace these statewide numbers, so look up your water first.

How to Measure Your Fish

Wisconsin defines fish length as the distance from the tip of the snout, in a straight line, to the utmost end of the tail fin, fully compressed.¹ That exact wording dictates how to measure.

Lay the fish flat on its side on a ruler or measuring board. Close the mouth and press the snout against the zero end. Pinch the tail lobes together so the tail reaches its full extent. The point where the compressed tail ends is the fish’s legal length. If that number falls short of the minimum by any amount, the fish goes back.

Three things trip people up. The mouth must be closed, not gaping with the jaw extended. The tail must be compressed, not fanned out naturally. You measure in a straight line, not along the curve of the body. Wardens carry their own boards and will re-measure anything in your cooler or livewell, so a borderline fish is rarely worth the risk.

Waterbody-Specific Rules and Slot Limits

Statewide defaults are the starting point, not the whole rulebook. Hundreds of Wisconsin lakes and rivers carry their own size limits, bag limits, and open seasons through NR 20.20’s county-by-county tables, and when a waterbody-specific rule exists it overrides the statewide default completely.¹

A protected slot limit defines a range of lengths in which all fish must be released. A lake might require you to release walleye between 15 and 20 inches, meaning you can keep fish under 15 inches (if they clear any applicable minimum) or over 20 inches, but nothing in the slot. The goal is to protect fish of peak spawning age while still allowing harvest at either end.

Some waters flip the concept with a maximum size limit, letting you keep only fish below a certain length to protect large trophy-class spawners. Others combine minimum lengths, slots, and reduced bag limits tuned to the health of that particular lake.

Muskellunge are where waterbody-specific rules bite hardest. The statewide default is 40 inches, but a large number of popular musky waters require 50 inches, and a handful near the Michigan border require 54.¹ Ten inches is enormous for a slow-growing species. Lakes like the Chippewa Flowage, Trout Lake, and many stretches of the Wisconsin River all sit at 50 inches. Assuming you can harvest a 42-inch musky because it clears the statewide default will earn you a serious citation if the lake you’re on carries a higher threshold.

The DNR maintains a searchable online regulation guide that lets you look up any inland lake by name or county and shows exactly which exceptions apply. Checking it before every trip is the single easiest way to avoid a violation.

Great Lakes and Mississippi River

The inland rules above do not control Wisconsin’s waters on Lake Michigan, Lake Superior, or the Mississippi River. Those systems operate under separate regulatory frameworks and often involve species, like lake trout, brown trout, and salmon, that rarely appear in inland tables. The Mississippi River boundary runs through the main channel, and your specific location decides which state’s rules apply regardless of where you launched or which state issued your license. Wisconsin publishes separate regulation sets for each of these waters.

Lake Sturgeon: A Category of Its Own

The 60-inch statewide minimum for lake sturgeon alone eliminates most fish from legal harvest, but the regulations go well beyond length. Before you can target sturgeon with hook and line, you need a valid carcass tag for the specific water you plan to fish. You can purchase only one hook-and-line sturgeon carcass tag per season for inland or outlying waters, plus one additional tag for Wisconsin-Michigan boundary waters. If you harvest a sturgeon, you must immediately validate the carcass tag, keep the fish openly exposed during transport, and register it with the DNR.⁴

If you hook a sturgeon incidentally while fishing for something else and you don’t have a valid tag, you must release it immediately.⁴

What a Violation Costs

A standard fishing violation carries a forfeiture of up to $1,000, plus a natural resources restitution surcharge on top. Penalties escalate with the value of the fish. If the combined value exceeds $300, the violation becomes a criminal offense carrying a $1,000 to $5,000 fine and up to 30 days in jail. Above $1,000 in value, it becomes a Class I felony.⁵

The court can also revoke all of your hunting, fishing, and trapping privileges for up to three years on top of any financial penalty, and a second conviction within five years triggers a mandatory one-year revocation of all approvals.⁵ Conservation wardens have authority to seize your boat, vehicle, or any equipment used in connection with the violation, and a court can order permanent confiscation.⁶

Sturgeon violations stand apart: $1,500 per fish, up to 90 days in jail, and a mandatory three-year revocation that a judge cannot reduce.⁵ No other species in Wisconsin’s fishing code carries that kind of mandatory loss of privileges.

1
Wisconsin State Legislature. Chapter NR 20 – Fishing
2
Wisconsin Department of Natural Resources. Total Daily Bag Limit
3
Wisconsin Department of Natural Resources. Difference Between Possession and Daily Bag Limit
4
Legal Information Institute. Wisconsin Administrative Code NR 20.07 – Lake Sturgeon Carcass Tags and Registration
5
Wisconsin State Legislature. Wisconsin Code 29.971 – General Penalty Provisions
6
Wisconsin State Legislature. Wisconsin Code 29.931 – Seizures