Fact Check

Was a 240-Pound, 7-Foot-Long, 100-Year-Old Fish Found in Detroit River?

This venerable lake sturgeon could well have been born during the presidency of Warren G. Harding.

Published May 3, 2021

 (U.S. Fish And Wildlife)
Image Via U.S. Fish And Wildlife
Scientists found a 240-pound, 7-foot-long lake sturgeon in the Detroit River in April 2021 that may be a century or more old.

On April 30, 2021, the Alpena Fish and Wildlife Conservation office — a branch of the U.S. Fish and Wildlife Service — shared news on Facebook of a "once in a lifetime" catch:

A once in a lifetime catch for our Detroit River native species crew last week! This real life river monster was tipping the scales at 240 lbs, measuring 6'10" long, and a girth of nearly 4'. Caught in the Detroit River, this fish is one of the largest lake sturgeon ever recorded in the U.S.

Based on its girth and size, it is assumed to be a female and that she has been roaming our waters over 100 years. So, she likely hatched in the Detroit River around 1920 when Detroit became the 4th largest city in America.

This fish was returned to the river after being processed by scientists from the Alpena office. That office, according to its website, deals with "conservation, restoration and management of the fishery resources of the Great Lakes Basin." The sturgeon catch was part of that office's native species restoration efforts:

The U.S. Fish and Wildlife Service’s mission is to preserve and restore native species. This is done by acquiring biological information on native species’ population status/trends, habitat availability/quality, controlling nuisance species and conserving habitat through protection, restoration and management. Restoration of native fish species and promoting healthy fish communities is a priority for the Alpena Fish and Wildlife Conservation Office.

Determining the age of a lake sturgeon is not an exact science. In the past, scientists have determined the age of these fish using relationships between certain scales or bones in a fish and its known age. While some of these methods have been further validated using radiocarbon dates, any age estimate will come with uncertainty, and that uncertainty increases with age.

Other more basic approaches have been created based on those aforementioned aging techniques. The Michigan Department of Natural Resources (DNR), for example, has created a simple chart that estimates age based only on length (from the sturgeon’s nose tip to the end of the dorsal lobe of the tail) and girth (the maximum circumference on the sturgeon’s body). Using this approach, an 82-inch long fish with a maximum girth of 48 inches is literally off the chart.

The closest approximation on that table would be an 80-inch-long, 35-inch-wide fish. Such a fish, according to the Michigan DNR, would have an estimated age of 153. Unfortunately, these numbers come with a great deal of uncertainty when you get to the larger end of the scale. What is certain, however, is that this is a huge old fish.

"We don't know the exact age of the fish," Justin Chiotti, a U.S. Fish and Wildlife Service biologist, told the Detroit Free Press. "But, to be 7-foot long and 240 pounds, the fish was likely 100 years old or older, and I think that's a minimum estimate, but I didn't want to get too crazy." An age of 100 years or so would put the fish's birthday somewhere in the administration of either U.S. President Woodrow Wilson or his successor Warren G. Harding.

Because the fish's size was confirmed by the scientists who captured it, and because there is a solid scientific rationale for concluding a fish of this size would be a century or more old, the claim that someone caught a 7-foot-long, 240-pound, centenarian fish in the Detroit River is "True."

Alex Kasprak is an investigative journalist and science writer reporting on scientific misinformation, online fraud, and financial crime.