Biologists with the U.S. Geological Survey are trying to bring Lake Sturgeon back to the Detroit River. The giant fish once spawned in the riverbed every spring before moving on to Lake Erie… now, the sturgeon are rapidly disappearing. The Great Lakes Radio Consortium’s Celeste Headlee reports:
Biologists with the U.S. Geological Survey are trying to bring Lake Sturgeon
back to the Detroit River. The giant fish once spawned in the riverbed every spring before
moving on to Lake Erie. Now, the sturgeon are rapidly disappearing. The Great Lakes Radio Consortium’s Celeste Headlee reports:
Sturgeon are the largest fish in the Great Lakes. The grayish brown creatures can grow up to
seven feet long, and weigh more than 200 pounds. Sturgeon have been on Earth for 100 million
years – 40 million years before the dinosaurs – and they have remained essentially
unchanged in all that time. Instead of scales, the fish have an almost leathery skin and five rows
of bony plates running along their torpedo-shaped bodies.
Fish biologist Bruce Manny says sturgeon were once abundant in the Great Lakes. Back in 1880,
in one month’s time, fishermen pulled four thousand of them from the Detroit River.
“They tore holes in their nets when they were fishing for other fish that they cared about. So
when they found a sturgeon in their nets, they would kill them, bring them to the shore, pile them
up on shore, dry them out and use them for fuel in the steamships. Burn them up.”
People didn’t eat a lot of sturgeon, but the creatures were caught and killed while fisherman
angled for more valuable fish. Scientists estimate that over-fishing has caused sturgeon
populations in all of the Great Lakes to dwindle to less than one percent of their
former number. The state of Michigan closed the Detroit River to all sturgeon fishing years ago.
Bruce Manny says he decided to check on the sturgeon and see if the fish population had started
Manny assembled a team of biologists from the U.S. Geological Survey. They started trapping
and then tracking sturgeon with electronic transmitters. Manny says he was surprised when his
team caught only 86 fish over course of four years. Manny says he realized the sturgeon
were in serious trouble and he obtained grants to investigate further. USGS scientists followed
the tagged fish for two years, and their patience was eventually rewarded. Manny found the first
known spawning site ever documented in Detroit River in modern times.
“We were excited all right. Eureka moment. I mean, this is like a very, very great coincidence
that we were able to find these spawning ready males, and they were able to find a female. When
there are only 86 fish caught in four years out here, there aren’t that many around. So to find
somebody to spawn with, so to speak, is a real challenge, I would say.”
The area where the sturgeon mated lies close to a sewer discharge pipe. There are limp, brown
grasses bordering grey, mucky water. Manny sent divers down and discovered the fish had
actually produced fertilized eggs. Manny says this was a major step forward for his project.
Sturgeon are pretty picky about their nesting sites. They need a fast moving current and several
layers of rock where the eggs rest safely. The problem is a lot of the gravel has been mined out of
the Detroit River for use in construction.
Another problem is the sturgeons’ longevity. Fish biologist Ron Bruch is in Wisconsin. He
oversees sturgeon populations in Wisconsin’s Winnebago River system. He says female
sturgeons live more than 100 years and they don’t spawn until they are at least 20 years old.
“Their life history works well for a long-lived species, but it doesn’t work well for a species that’s
exploited heavily. So, sturgeon can only tolerate very low exploitation rates, and when the
exploitation is high the populations collapse.”
Wisconsin was the first state in the U.S. to create a sturgeon management program, more than
100 years ago, and the fish are abundant there.
Bruch says that’s why many other states have come to him for advice on how to strengthen their
sturgeon populations. He helped build the first man-made Lake Sturgeon spawning site and he
thinks a program started in Michigan has a good chance to succeed.
Bruce Manny plans to build three sites, using limestone, coal cinders and gravel. He’ll monitor
them closely to determine which kind of rock the fish prefer. Manny says he doesn’t mind
spending so much time with sturgeon. He says he admires the fish, and imagines that
each of them has a distinct personality.
“I wish they could talk to me and they do in some ways, because some of them have scars and
evidence of propeller hits which show that they’ve managed to take that sort of punishment and
survive it spite of it all. You know, they’re long-lived, they’re survivors, they’re
tough, and they’re successful.”
Ron Bruch it’ll be 100 years before fisherman will reel in these huge fish. He says many
generations of biologists will have come and gone before the sturgeon population is firmly
reestablished in the Great Lakes. And biologists, he says, will have to create a lot more
spawning sites like the ones in the Detroit River.
“In and of itself, it’s not going to restore all of Lake Erie or all the Great Lakes, but it’s a shining
example of what can be done in many areas around the Great Lakes to help produce Lake
Sturgeon spawning habitat and rehabilitate the Lake Sturgeon population.”
It’ll cost about half a million dollars to build the three fish nesting sites. Officials say they’ll be
ready in time for the sturgeon’s spawning season next May. If the project is successful in the
Detroit River, biologists hope to expand the program into other areas of the Great Lakes where
sturgeon were once abundant.
For the Great Lakes Radio Consortium, I’m Celeste Headlee.