Crews with the U.S. Fish and Wildlife Service and the Michigan Department of Natural Resources, along with the Ohio DNR, are searching Lake Erie for Asian carp this week.
They’re stepping up their sampling efforts because of lab results that showed six water samples from Lake Erie had positive environmental DNA hits for Asian carp. Those water samples were from August 2011.
The teams are now out on the lake to see if they can find any more evidence of bighead or silver carp in the lake.
Todd Kalish is the Lake Erie Basin Coordinator with the Michigan DNR. He says a positive eDNA sample could mean there are live Asian carp in Lake Erie... but there are other possibilities.
"A positive DNA sample basically means that some part of a carp was left behind within 24 hours of a sample being taken. And so it could’ve been a scale or mucus or excrement. Basically what it tells us, and what we assume, that environmental DNA means there was a silver or bighead carp in that area within 24-48 hours of the sampling."
He says the U.S. Army Corps of Engineers is conducting a study to identify other possible ways carp DNA could get transferred from one lake to another. Kalish says if they find a live carp this week, they'll follow the procedures laid out by the state's management plan.
"If a live bighead or silver carp is collected, one of the first things we will do is get as much information about that fish as we possibly can. And so, the fish would be taken to an Ohio DNR or Michigan DNR facility. We would determine whether or not it was reproductively viable, we would age the fish, and then there would also be an enhanced sampling protocol."
Kalish says right now, there's no evidence there's a reproducing population of bighead or silver carp in Lake Erie. But he says if that happens in the future, there could be some significant negative effects on the fisheries communities.
"Lake Erie and Lake St. Clair, which are connected, they provide really good habitat for silver and bighead carp, and we have a very good fisheries community in those two lakes right now. The walleye population is very good and the yellow perch population is good; we’ve got smallmouth bass in both of those lakes, and those populations would likely be impacted if there were a reproducing population of silver or bighead carp within Lake Erie or Lake St. Clair."
We’ve also had other carp news lately. The Michigan DNR announced last week that a grass carp that was caught in the St. Joseph River in southwest Michigan and it was capable of reproducing. I asked Todd Kalish how concerned the DNR is about that discovery:
"That’s a big deal. Grass carp are a prohibited species in the state of Michigan. And so grass carp are illegal to transport or have in your possession alive. Grass carp are extremely voracious, so they can eat 40-50% of their body weight in one day, and they specifically target vegetation, so they can remove significant amounts of vegetation, which is really critical to sustain a healthy aquatic ecosystem."