LANSING, Mich. — A water sample taken from the Kalamazoo River last summer has come out positive for environmental DNA (eDNA) for silver carp. The water samples take several months to evaluate, according to the Michigan Department of Natural Resources (DNR).

The announcement came earlier this month in a joint statement from the DNR and U.S. Fish and Wildlife Service. The positive result in the sample represents a first for silver carp eDNA in Michigan’s Great Lakes waters, aside from Maumee Bay off of Lake Erie.

Two-hundred water samples were taken in July along the Kalamazoo River, from below the Caulkins Dam in Allegan County to the mouth of the river. One of those samples tested positive. The DNR received the results Oct. 2. Another 200 samples of eDNA in water were also collected one month prior to that, in June, but those tests resulted in no positive results. “Although not conclusive, this finding heightens our vigilance and sets into motion a specific response,” said DNR Director Keith Creagh. “We will work with our partner organizations and anglers on next steps to protect the Great Lakes and its tributaries against this significant threat.”

Silver carp is one of two species commonly referred to as Asian carp, aggressive fish not native to the United States and which are widely seen as a nuisance – or worse. The fish, which include silver and bighead carp, are thought to have been brought into the country to help aquaculture operators in the South clean fish ponds; however, they later escaped and became established in the Mississippi River.

During a period of perhaps 20 years, the fish made their way north until they penetrated the Chicago Sanitary and Ship Canal, which connects the Mississippi River basin to the Great Lakes. A bighead carp was caught in 2010 in Lake Calumet along the shores of the Chicago Area Waterways System.

Currently, there is a program to stop the fish in that area via an electric barrier. Officials have also been known to do fish kills and other practices to monitor for the presence of Asian carp.

The fish grow to weigh as much as 110 pounds and have been filmed jumping out of the water en masse over the sound or vibration of a passing boat. There have been reports of people being injured when a fish jumps into a passing boat, slapping the boater in the face or jaw.

There is disagreement, however, over whether the fish would thrive in Great Lakes waters, which are deep compared to the Mississippi River and its tributaries.

Michigan officials caution this latest finding does not mean silver carp are now established in the Kalamazoo River. The findings represent the presence of genetic material of silver carp, such as scales, excrement or mucus. But that material could have been brought in via boats, fishing gear and the droppings of fish-eating birds, they say.

“Positive detections do not tell us about whether silver and or bighead carp have established, just whether they are likely present or not,” said William Chadderton of The Nature Conservancy.