Yes, not a big issue in Lake Michigan proper, most likely, for the reasons you listed. But the concern is once they are in the Great Lakes watershed, they are going to be very difficult to stop from spreading immensely.
New research has show that asian carp need much shorter distances of free-flowing river to reproduce than previously thought, which is extremely concerning. In fact, grass carp have successfully reproduced in the Sandusky River, which is only 14 miles long. Other research has identified 16 miles of river as the new minimum. It's very possible that new research could find it's even less than that. Fast growing, highly fecund species like asian carp produce a lot of offspring and show a lot of potential for adaptation/evolution
cida.usgs.gov/glri/projects/invasive_spe...t-suitability-8.html
voices.nationalgeographic.com/2013/10/31...eat-lakes-tributary/
www.researchgate.net/profile/Reuben_Gofo...Novel-Ecosystems.pdf
Modeling work has identified over 25 rivers that have high certainty of sustaining asian carp, particularly bighead and silver. And unfortunately, researchers keep finding asian carp spawning activity in smaller and smaller streams that show they can and will utilize much different spawning conditions than previously thought. Meaning that a heck of a lot more than 25 big rivers would be able to be colonized.
Knowing what we know right now, they would be an unmitigated disaster in our big rivers, drowned river mouths, Lake St. Clair, Lake Erie, etc.
Think about the St. Joseph, Muskegon, Grand, Sandusky, Saginaw River (and Saginaw Bay), Lake St. Clair, Detroit River, Lake Erie, Maumee River infested with asian carp. It would be very, very bad
One study estimated that 34% of all fish biomass in Lake Erie could eventually be silver carp. In some areas of the Illinois River, over 80% of the fish biomass is asian carp.
I hate to sound all doom and gloom, but this is essentially on par with zebra and quagga mussels in terms of ecosystem disruption. And we KNOW what happened there. If we had a chance to go back in time and prevent that, we would do it, right? It wouldn't even be a question!
We have a chance to prevent Asian Carp from entering the Great Lakes watershed. I hope we don't screw it up