Sandusky, Ohio — On July 30-31, the Ohio DNR, Michigan DNR, U.S. Fish and Wildlife Service (USFWS) and U.S. Army Corps of Engineers collected 150 water samples from the Sandusky Bay and Sandusky River.
Analysis of these water samples indicated 20 samples out of 150 taken from throughout Sandusky Bay and Sandusky River have tested positive for the presence of silver carp environmental DNA (eDNA).
The eDNA samples were collected as part of extensive sampling effort conducted earlier this summer for Asian carp in Sandusky Bay and Maumee Bay in western Lake Erie. No Asian carp were found through intensive electrofishing and test netting. Maumee Bay eDNA results are currently being analyzed.
“We will continue to address the uncertainties about the status of Asian carp in Lake Erie with our partner agencies,” said Rich Carter, ODNR executive administrator of fish management and research. “This includes ramping up our search efforts for live fish or other sources of eDNA. We will keep working with our angling public to be vigilant in watching for these species.”
In response to the positive findings, both state and federal officials have already started collaborative discussions to implement additional investigative work in early September, including additional eDNA testing. All parties continue to work together to assess the current status of bighead and silver carp within western Lake Erie bays and select tributaries.
Researchers say eDNA analysis provides a tool for the early detection of Asian carp at low densities, and these latest positive results heighten concern about the presence of Asian carp in western Lake Erie. However, the analysis cannot provide or confirm information about the number or size of possible fish.
At present, eDNA evidence cannot verify whether live Asian carp are present, whether the DNA may have come from a dead fish, or whether water containing Asian carp DNA may have been transported from other sources such as bilge water, storm sewers, or fish-eating birds. The USFWS, U.S. Army Corps of Engineers, and the U.S. Geological Survey are leading a two-year Asian Carp Environmental DNA Calibration Study, funded through the Great Lakes Restoration Initiative to reduce the uncertainty surrounding Asian carp eDNA results.
“The breadth of positive samples from the Sandusky Bay area was not expected,” said Michigan DNR Fisheries Chief Jim Dexter. “We need to understand the source of the eDNA in order to address it and keep silver and bighead carp from establishing a viable population in the Great Lakes.”
Since extensive sampling conducted for this species this summer, as well as extensive sampling conducted historically, have yielded no live fish, the data suggests that if Asian carp are present, then they are in very low abundance.
“These eDNA samples provide useful information to help guide our monitoring of Lake Erie and our response to any threat of Asian carp to the Great Lakes,” said USFWS Midwest Deputy Regional Director Charlie Wooley. “While there is still uncertainty about the source of eDNA, the recent findings provide another point of data as we work with Ohio and Michigan to assess the status of Asian carp in the area. I want to stress that recent fish sampling activities, such as gill netting and electrofishing, have not provided any physical evidence that live Asian carp are present in western Lake Erie.”
Asian carp, including bighead and silver carp, pose a significant threat to the Great Lakes ecosystem and economy. Help from the public, especially Great Lakes anglers, will be imperative moving forward. All anglers are highly encouraged to learn how to identify Asian carp, including both adults and juveniles, as the spread of juvenile Asian carp through the use of live bait buckets has been identified as a possible entry point into the Great Lakes. A video teaching people how to identify bighead and silver carp is available on the USFWS’s YouTube channel.
If anglers or constituents have observed or captured an Asian carp, immediately notify ODNR at 800-WILDLIFE (945-3543). Photograph the fish from nose to tail, and retain the fish on ice for verification. Photographs can be sent directly to ODNR at wildohio.com by clicking on the Asian Carp link and following the instructions.
Identification guides, frequently asked questions, and management plans are also available online at www.michigan.gov/asiancarp and www.wildohio.com.
To learn more about eDNA sampling and filtering in Sandusky Bay, view images of the process here.