Who would imagine that a fish could wipe out a fishery? Experts says it’s a real possibility if the grass carp starts reproducing in the Great Lakes. Kinda reminds one of the raptors in the movie “Jurassic Park,” except we’re talking real life here.
There’s been lots of publicity about the fight for years to keep both the from moving up the Illinois River and entering Lake Michigan at Chicago. In fact, millions of federal and state dollars are being poured into the Brandon Road Lock and Dam about 47 miles south of Chicago for electric fences, sound barriers and bubble curtains that, so far, have kept these notorious carp from reaching the Great Lakes.
A third variety of Asian carp, the grass carp, has been swimming below the radar. They’ve now been found in the four lower Great Lakes and even appear to be spawning in Lake Erie.
It has been well documented that the ravenous-feeding bighead and silver carp, if allowed to enter the Great Lakes, are genuine threats to wipe out all native species of fish by consuming their feedstocks. The grass carp doesn’t eat fish. Rather, it’s a voracious herbivore that has actually been found in Lake Erie since the early 1980’s. But it hasn’t been considered a threat because it’s supposed to be sterile and can’t reproduce.
Or can it?
Federal and state fisheries managers have assumed that grass carp are sterile, as is required by law in some states. So, this fish has been approved for import to control unwanted vegetation and algae in such bodies as private ponds and golf course water hazards. But of 53 grass carp captured in the Michigan and Ohio portions of Lake Erie, 85 percent were determined to be fertile. Moreover, newly hatched grass carp and fertilized eggs have also been recovered, all but confirming the species is reproducing, according to recent reports in the Chicago Tribune.
Great Lakes states Ohio, Pennsylvania, Illinois, Indiana and New York allow grass carp to be imported and raised, as long as fertilized eggs are sterilized through drastic changes in temperature or pressure. Minnesota, Wisconsin and Michigan ban grass carp.
“This seems like a terrible idea,” Molly Flanagan told the Tribune. She is vice president of policy for the Chicago-based nonprofit Alliance for the Great Lakes. "It seems like all states should ban possession of grass carp. We know they pose a threat to the Great Lakes. We know you can’t tell by looking at the fish whether it’s sterile or fertile. So why would we allow anyone to possess this fish? It doesn’t make any sense.”
The U.S. Fish and Wildlife Service reported 20 grass carp were recently captured in Ohio’s Sandusky River and 10 were fertile. It is believed that a sustained grass carp population could devastate the already dwindling wetlands in the Great Lakes. They report less than half of the historical coastal wetlands in the Great Lakes basin still exist today. And, the half-million acres left are already threatened by pollution, development and invasive species.
So, while the silver and bighead carp would compete directly with Great Lakes native fish for food, grass carp would consume the vegetation that provides vital habitat for some species of juvenile fish and other wildlife.
Further, it’s not just a fishing problem. Grass carp would also harm beaches and coastal areas. Shoreline erosion could increase without the roots of wetland plants holding them in place. Without further efforts to stop grass carp, the socioeconomic costs to commercial and recreational fishing in the Great Lakes is projected to be $15.3 billion over a 40-year period, according to a binational risk assessment of grass carp led by Fisheries and Oceans Canada.
To add to the problem, reports indicate the Midwest’s historic rainfall and flooding this year could advance the spread of grass carp in the Mississippi River basin and the Great Lakes. Again, the U.S. Fish and Wildlife Service has reported grass carp have been captured in states like Iowa, Nebraska and Missouri. It’s suspected that the flooding of outdoor ponds is how they escaped captivity. Many of these ponds are connected to the Illinois River by smaller waterways, allowing fertile grass carp to invade.
So far, experts believe migration has been limited, and Lake Erie is believed to be the only known location where grass carp are spawning. But research suggests they may have even more staying power. Fisheries and Oceans Canada says there are 57 rivers in the Great Lakes basin that could provide suitable spawning habitat. And the species, which grow to nearly 100 pounds, has few predators.
Anything that threatens the health of any of our nation’s fisheries is a concern for the future of our boating industry. And while many decision-makers are gathered this week at ICAST, the huge fishing tackle trade show in Orlando, it could be time for our industry to develop an appropriate position regarding the continued importation or commercial raising of grass carp in our country.