Asian Carp Found In Lake Erie Watershed

Here's some bad news:

Lake Erie has its own problems. There, a chain-link fence separates a flood-prone wetland between two rivers—one that flows toward the Mississippi and another that flows into Lake Erie.
Several grass carp (one of the Asian carp species) have been caught in or near Lake Erie in recent years. However, the ones that were discovered were sterile. Sterile fish are used to control plant growth, and they can't reproduce because they are triploid—having a triplicate set of chromosomes.
In October of last year, four smallish grass carp were caught in a river just a couple miles upstream from Lake Erie. The results of tests performed on the fish have now been published, and the news isn’t good. The fish weren’t sterile like the others, and they were only about a year old.
To determine where the fish had come from, researchers measured the amount of strontium in a bone inside the fish’s ears. The river in which the fish were found happens to have higher than average levels of strontium in it, and that’s what they found in the ear bones as well. In fact, the inner part of the bones, which formed early in life, contained significantly more strontium than the outer portion. That matched up with strontium in the river, which was high during a wet 2011 and low during the drought in 2012.
That means the grass carp appear to have hatched in the river, making this the first documented instance of Asian carp reproducing in the Lake Erie watershed.
The researchers write, “The implications that grass carp have spawned and recruited in the Great Lakes Basin are profound.” In habitats like Lake Erie, grass carp populations are capable of grazing lake-bottom plants basically down to nothing. If they can establish a population, it would mean trouble for the rest of the Lake Erie ecosystem, including the native fishes and birds that rely on those plants.
What’s more, it had been thought that grass carp required a longer river than this one for spawning. The apparent success in this instance means that grass carp—and the other species—might have an easier time establishing a foothold in Lake Erie than expected.

Looks like the invasion may have begun, at least in the eastern part of the Great Lakes.