December 23, 2016
DETROIT — The news is mixed as Great Lake states and the federal government continue to devote money and brainpower to stopping a potential Great Lakes ecological disaster — invasive Asian carp species making their way from the Mississippi River into Lake Michigan.
First the good news: The leading edge of the mass of bighead and silver carp hasn’t made much progress lately up the Mississippi and connected rivers toward Lake Michigan.
“We really haven’t seen the picture change for silvers and bigheads over the last few years,” said Charles Wooley, deputy director of the U.S. Fish and Wildlife Service’s Great Lakes Region. “That’s really a good thing for those of us who are working on this.”
Now the bad news: The younger fish — juveniles — are moving closer, the evidence shows. And they can do more damage.
“The bottom line is that the juvenile front is advancing, and made a big jump last year,” said Joel Brammeier, president and CEO of the non-profit Alliance for the Great Lakes. “And we still don’t have a permanent solution in place that’s going to solve this problem.”
The little guys are a big concern. Only three lock-and-dam systems and two electrical barriers — which aren’t effective on juveniles — remain between the invaders and Lake Michigan. And the heavy ship traffic to and from Lake Michigan and the Mississippi can disrupt the effectiveness of electrical barriers and otherwise help the fish slip through locks and closer to the lake, said Daniel O’Keefe, Southwest District educator for the non-profit Michigan Sea Grant and Michigan State University Extension.
“It seems like the wolves are at the door, and the door is still opening and closing,” he said.
At stake, potentially, is the $7-billion Great Lakes fishery. Bighead and silver carp — fish farm escapees up the Mississippi River after being imported into the southeastern U.S. in the 1970s to remove algae out of catfish farm and wastewater treatment ponds — grow fast, eat voraciously and breed prolifically. A single female can produce a million eggs or more, and the fish can grow up to 100 pounds. Scientists believe the invaders would outcompete native species and Michigan’s prized sports fish, creating ecological chaos on the Great Lakes.
And there’s another, more direct, potential danger from silver carp: Their propensity for leaping out of the water, as much as 10-15 feet. “Just think about Jet-Skiing or water-skiing and getting hit by a fish that can potentially be 40 pounds or bigger. That’s a big health concern,” said Seth Herbst, the Michigan Department of Natural Resources’ aquatic invasive species coordinator.
On the good news side, the Michigan Department of Natural Resources announced in late August that its annual survey of Michigan’s Great Lakes major tributaries, conducted with the Fish and Wildlife Service, found no bighead or silver carp environmental DNA, or eDNA — DNA extracted from the water or soil without a specific fish or animal on hand.
On the bad news side, the front of bighead and silver carp that are reproducing has moved closer to Lake Michigan than ever before — 90 miles closer to the Great Lakes just last year, O’Keefe said.
Silver carp larvae were found in the Dresden Island Pool of the Des Plaines River, about 47 miles from Lake Michigan, in June 2015. Since young fish tend to drift with the currents, that means they were probably hatched about 10 miles even farther upriver, somewhere in the vicinity of the Brandon Road Lock and Dam near Joliet, Ill., O’Keefe said.
An Illinois program to harvest Asian carp near Peoria has helped keep adult numbers from spreading quickly, Herbst said. That program has removed nearly 4.5 billion pounds of Asian carp since 2011, most being exported for human consumption in China.
But that approach has its limits, O’Keefe said. The Chinese market is primarily for adult, bighead carp, he said. There’s less of a market for the silver carp that make up the bulk of the biomass making its way up the river. And commercial fishing is more viable farther down the Mississippi River; but near the leading edge of the invaders in the Illinois and Des Plaines rivers, there aren’t enough carp to make commercial fishing viable unless it’s continually subsidized, he said.
Current markets also want adult fish, while managers seek to remove fish of all sizes.
“What’s needed is a market for both fish, in varying sizes — pet food, fish oil,” O’Keefe said. “No one’s been able to develop a market for that at this point.”
While there’s no long-term data that can predict what will happen yet, “We’re getting a little glimpse that we may have reached a stalemate in this movement, which is good,” Wooley said.
Lake Michigan and the Mississippi river were originally connected in 1848, in a limited shipping canal system. To deal with a rapidly expanding Chicago’s sewage overflows into Lake Michigan, a sanitary canal was built between the Chicago and Des Plaines rivers to move sewage to the Mississippi by 1900, which included engineering work to reverse the flow of the Chicago River from Lake Michigan in the opposite direction to the Des Plaines River.
The U.S. Army Corps of Engineers operates two electrical dispersal barriers near Romeo, Ill., about 37 miles south of Lake Michigan. A third electrical barrier upstream of the existing pair is also in the works, with an aim of making it more effective against juvenile fish, Wooley said. The Army Corps expects to have that completed sometime next year.
“There are no fish that are probing these electrical barriers on a daily basis,” Wooley said. “The closest these fish are is about 15 to 20 miles downstream, and that leading edge hasn’t really changed much in the past five or six years.