Six water samples collection from Sandusky and north Maumee bays in Lake Erie have tested positive for the presence of Asian carp environmental DNA (eDNA), according to the state Department of Natural Resources.
The six samples were among the 417 collected from Lake Erie in August 2011 and analyzed and confirmed by eDNA researchers earlier this month. Four samples from Sandusky Bay tested positive for bighead carp eDNA, and two samples from north Maumee Bay in Michigan waters were positive for silver carp eDNA.
Both fish are among four species of Asian carp considered to be major threats to the Great Lakes and have been found in the Illinois River.
While the water samples were positive for eDNA, there is no physical evidence that the fish have migrated to the Great Lakes.
Nevertheless, electro-shocking and netting has taken place in Sandusky Bay, while additional testing and monitoring efforts are planned by the Ohio and Michigan departments of natural resources.
“The results from these water samples are certainly concerning as this marks the first time Asian carp eDNA has been detected in water samples from Lake Erie, or any of the Michigan waters intensively surveyed for the presence of invasive carp,” said Michigan Department of Natural Resources (DNR) Fisheries Division Chief Jim Dexter. “Protecting the Great Lakes from the threat of Asian carp is critical to the health of our sport and commercial fisheries and to the quality of life in Michigan. We are actively engaged in Asian carp surveillance programs throughout the Great Lakes, including Lake St. Clair and Lake Erie, and the department stands ready to take the necessary and appropriate actions to investigate and respond to these results.”
Asian carp, first imported to control algae in fish farms along the Mississippi River, escaped during a flood event in the 1990s. Since then, the carp have moved quickly up the Mississippi River and into the Illinois River, the Des Plaines River, the Chicago Sanitary and Ship Canal, and the Calumet-Sag Channel.
Concerns about Asian carp invading Lake Michigan grew in 2010 when the first live Asian carp, a Bighead carp, was caught beyond electric barriers in Lake Calumet, just six miles from Lake Michigan. That discovery has sparked debate on a proposal to spend up to $9.5 billion to separate the Mississippi River Watershed and the Great Lakes.
Asian carp can weigh up to 100 pounds, grow to a length of more than 4 feet and, on average, eat up to 20 percent of their body weight in food each day. They are also extremely prolific. As such, Asian carp pose a major economic concern as they would outcompete other Great Lakes fish species if they invade the Great Lakes.
Should the Asian carp get into the state’s inland lakes, especially in an area like Oakland County, their impact on the inland lakes’ ecosystems could be devastating, as well.
“When it comes to the spread of Asian carp, we are very concerned about inland waters,” said Tammy Newcomb, research program manager for the DNR Fisheries Division. “(Asian carp) can spread from the Great Lakes (into inland waters) just by moving naturally up the waterway. And we know that Asian carp do very well in small inland waters. While a spawning population may not be produced in such waters, if a number of them occupy the inland lake, it could disrupt that system’s food web.”
eDNA is a genetics tool developed by researchers at Notre Dame and the Nature Conservancy which detects the presence or absence of species-specific DNA in an aquatic environment, such as the cells shed by Asian carp through their feces, urine, mucus, and gills.