Living dinosaurs

The Lake Sturgeon in the St. Croix and Namekagon Rivers are an ancient, unique and delicate fish species.




3 minute read

Deb Ryun is the executive director of the St. Croix River Association, a St. Croix 360 partner.

Lake Sturgeon in the Yellow River, Burnett County, WI-Photo by Jeffrey Kampa, Wisconsin DNR
Lake Sturgeon in the Yellow River, Burnett County, WI-Photo by Jeffrey Kampa, Wisconsin DNR

The St. Croix and Namekagon Rivers are part of the National Park known as the St. Croix National Scenic Riverway. It is a unique river system, with high water quality and good habitat that provide for an incredibly diverse fishery. This system supports world-class sport fishing, known for its smallmouth bass, muskellunge, and lots of other species.

People come from around the world to fish these waters. But to me, the most impressive fish that can be found here is the sturgeon.

Gentle giants

Lake sturgeon can be found on the Namekagon from the Trego dam, near the County K landing all the way down to the confluence of the St. Croix. They grow to be huge and old, growing to 84 plus inches long, over 100 years, and well over 200 pounds.

The largest lake sturgeon on record was caught from Lake Winnebago, in eastern Wisconsin. It was 87.5”, 240 pounds, and approximately 125 years old. Sturgeon mature late, and start reproducing after 15-20 years for males, and 20-25 years for females.

As a group, sturgeon appeared over 100 million years ago. They are often referred to as the dinosaurs of fresh water fish.

Friendly fish

If you’ve ever been on the Namekagon River in a boat, you know how rocky and shallow it is in many segments. The thought of a fish that big living in these shallow waters is really amazing.

Those of you who’ve been on the river also know how clear the water is. If you stand in a boat and drift along, it can be like looking into an aquarium. These sturgeon tend to be very docile and unafraid of humans; if you’re out there paying attention, you’re likely to see them.

In some cases you don’t have to pay such close attention. The big ones can leave a wake as they swim along, and some times of year they “breach”, or jump up out of the water.

Careful management

In the national park above the dam at St. Croix Falls there is no fishing season for sturgeon. While in some areas they are naturally reproducing, their numbers are not strong enough to allow fishing.

Over the years, a number of factors had led to their decline. Point source pollution from industry dirtied the water. Fish were cut off from spawning grounds by dams. Sturgeon were fished to the point where their numbers were no longer sustainable.

Since then, there have been terrific advances to help sturgeon and other plants and animals that count on rivers to survive. The Clean Water Act led to improvements in river systems, correcting much of the point source pollution. Fish passage over or around barriers is complex, but in some cases fish ladders have worked, and in other areas sturgeon have been reintroduced to restore the fish.

Exploitation is the most manageable variable. That is why there are limits on fishing with a short or no season, tag requirements, or high minimum length limits.

The Departments of Natural Resources of both Minnesota and Wisconsin and the National Park Service cooperate to manage for sustainable populations where lake sturgeon exists in the border part of the St. Croix. Below the dam in St. Croix Falls there is a very limited fishing season, but the rules are very strict so be sure to check fishing regulations if you intend to try your luck fishing for sturgeon.

Next time you are on the river, pay attention to those big submerged logs, they might our living dinosaurs.