None of the 180-plus invasive species found in or threatening the Great Lakes have more name recognition among average citizens than the Asian carp. Though people have heard of zebra mussels, only a relative few have heard of quagga mussels. Many experts point to quaggas as the most environmentally damaging invasive species to ever infest the Great Lakes.
Still , of all the invasives in the Great Lakes — the mussels, the lampreys, miniature freshwater shrimp and all the rest — none are as well known as the YouTube stars — the “flying carp.” No doubt you’ve seen those big silver carp jumping into boats in middle America’s big rivers. Too bad zebra and quagga mussels and other invasives weren’t as photogenic and engendered an equal amount of dollars and concern when they first invaded the lakes.
The flying carp are named silver carp — they are the jumpers. They, along with their cousins, bighead, black and grass carp are often grouped together as Asian carp. All of them are serious problems in middle America’s rivers.
When I get questioned by someone about invasives in Lake Michigan (or the other Great Lakes) almost always the question is about Asian carp. You’d think the lakes are swarming with them. They aren’t, though the Mississippi, Missouri, Ohio, Illinois and others are and the potential does exist for the swarms to spread on northward and eventually get into the Great Lakes.
No one wants that to happen and the easiest way to quantify the magnitude of the damage should they get into Lake Michigan and then spread to the other lakes is to express it in dollars and cents. Hurricane Sandy caused $62 billion in damage. Western wildfires cost $18 billion last year. Disasters seem to be best understood, comprehended or compared that way. How else would you compare a flood with an earthquake with a hurricane? What is the economic damage?
The dollar figure most often used to warn of the economic damage to the Great Lakes should Asian carp become established is six billion dollars annually to the “fishing industry” which I assume is a cumulative figure combining the economic impact of both recreational fishing and commercial fishing.
When a person sees this number, the A follows B reasoning is A) should the carp proliferate in the Great Lakes then B) they will somehow displace the salmon, trout, walleye, whitefish, perch and other species people harvest from the lakes.
Not so much. Asian carp feed by filtering algae, plankton and other nearly microscopic “edibles” from the water. This is the same thing baby fish feed on their earliest stages of life and the same things the slightly larger things like freshwater shrimp eat. Once baby fish grow, they switch to feeding on shrimp and other zooplankton before ultimately switching to eating other fish.
If the carp get established in the lakes, the next logical step is they’ll vacuum out enough algae, plankton and the rest of the stuff at the bottom of the food chain to starve the sport and commercially important fish. Eventually, they will eliminate six billion dollars worth, each year.
Except for one thing, the invasive mussels have already done that. Lake Michigan’s water is now more clear than Lake Superior’s water. (Lake Michigan has far more zebra and quagga mussels.) Lake Michigan is also ground zero as the location Asian Carp could most readily access the Great Lakes because of it’s connection via man-made waterways to the mid-American river system.
If the mussel invasion already sucked the life from the bottom of the food chain, would the Asian carp exacerbate it? Hardly, most Asian carp, were they to freely swim upstream from the Illinois River into Lake Michigan, would quickly starve to death. There’s not enough algae and plankton in the lake to keep them healthy for long.
But maybe one in a hundred would live in the lake long enough to find, say the Root River in southern Wisconsin, Trail Creek in Indiana or the St. Joseph River in southern Michigan. Maybe only one in a thousand would find a new home in these or other tributary streams. But if they did, they could proliferate in them and a new invasion would occur. From the St. Joe to the Black River. From the Black to the Kalamazoo or the Grand and on up the coast.
Eventually, should this happen, much of the northeastern United States and southeastern Canada could be infiltrated by flying carp and the cousins. That’s the real threat of letting Asian carp gain access to the Great Lakes. If that were to happen, the economic damage would make the six billion dollar figure now bandied about seem insignificant.