Lydia Lohrer

Special to the Detroit Free Press

The Detroit River flows in the background of city life, often unnoticed.

But beneath, dinosaurs lurk.

This past week, the U.S. Fish and Wildlife Service caught a 120-pound sturgeon in its depths.

An ongoing survey, funded in large part by Great Lakes Restoration Initiative dollars, studies these ancient fish. Hunting and fishing licenses also play a role in the conservation of the species, as the USFWS partners with Michigan’s Department of Natural Resources in various restoration programs.

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Angler makes rare catch on Detroit River, reels in Atlantic salmon

Fisheries technician Paige Wigren tells the story, “It’s estimated that in the 1800s we had over a million of these fish in the Detroit/St. Clair River system. Today, less than 1% remain. The good news is that they seem to be increasing in abundance.”

Around half of the state’s sturgeon population resides in the Detroit/St. Clair River system. In this part of the Great Lakes “we have captured lake sturgeon up to 7 feet long that weighed almost 200 pounds. Fish that size can be upward of 100 years old,” said senior biologist James Boase.

Considered nuisance fish by commercial anglers who caught them in their nets in the mid-1800s, they were pulled from the water and stacked up on shore. Sometimes, they were burned for fuel because of their high-fat content. Sturgeon eggs became popular for consumption, and their numbers continued to plummet.

“Recently, we built four artificial spawning reefs designed to attract bottom dwelling species like sturgeon, and research by our colleagues at the USGS Great Lakes Science Center shows that the reefs are definitely working,” said Wigren. "We run a 600-foot trot line with around 50 hooks. We bait it with invasive gobies caught out of the Detroit River and let them set for a 24-hour period. We collect information such as their total length, look for lamprey wounds and even carry an ultrasound to determine the sex of the fish,” said Wigren.

Related:

School, Dept. of Natural Resources bring elementary students to the classroom at the river

Sturgeons spawn infrequently. Males don’t reach sexual maturity until they are 10-15 years old and females can be as old as 25. The ratio, says Wigren, matters.

Each year, Detroit students are invited to Milliken State Park to meet a sturgeon.

“This week, Maltby Middle school joined us, and a number of other partners and they got to meet a 75-pound male sturgeon captured that week. They learn about the life cycle of the fish in the classroom and then actually come face to face with a dinosaur,” said Wigren. “Most of the kids have no idea this underwater world full of sturgeon even exists.”

“Each fish tagged with a PIT (pass integrated transponder tag like a microchip) and also fitted with a yellow tag with a dorsal fin and office phone number in case an angler catches one. We can tell when it was tagged.”

The U.S. Geological Survey also has about 300 sturgeons fitted with acoustic telemetry receivers, which can offer real-time tracking.

As far as the Detroit River sturgeon, Wigren suspects most sturgeons captured in the Detroit River may be residents, not wanderers. “Information collected from the telemetry study tells us that most of the Detroit River sturgeon are resident fish who don’t stray very far. The point of this study is to get a better population estimate of how many are in the system. It’s great to see recaptures, but at the same time, our estimated population goes down every time we catch the same fish. This year we’re on recapture No. 7 within a month of sampling. So, we may have less of them than we hoped.”

Lake sturgeon harvest is limited to one per year per angler, and only on certain waters. Any sturgeons captured in the Detroit River must be immediately released, but on Lake St. Clair and the St. Clair River in Michigan, anglers may harvest one between July 16 and Sept. 30 with a slot size limit of 42-50 inches (inclusive).

Port Huron is hosting the annual Blue Water Sturgeon Festival from 10-4 p.m. June 3. Admission is free. Family friendly activities include a live sturgeon touch tank, sturgeon birthday cake, poster contest and a run with sturgeon marathon. Go to sturgeonfestival.com for more information.

Contact Lydia Lohrer: lydiaoutdoors@gmail.com.