Photos for Muskingum River/Asian carp eDNA story. Old, deteriorated locks at Philo/Duncan Falls dam, downstream from Zanesville, on the Muskingum River. The Blade/Matt Markey
The mysterious fingerprints were there. The unwanted intruder left at least 10 of them, enough to shake up the locals and prompt a call to bring in the cavalry for a search and destroy exercise.
But as is often the case with Asian carp, the suspects possibly slipped away, if they had been there at all, and now the plot only thickens.
In April we learned from a report released by the Nature Conservancy and several other entities that a number of water samples taken from the Muskingum River had tested positive for the environmental DNA (eDNA) of bighead carp.
The term eDNA refers to genetic material, which could be present from scales, body fluids, blood, waste, or live fish being in the water. Biologists use eDNA analysis of water samples as an early detection tool to determine if Asian carp are present in a waterway. Finding eDNA confirms only the presence of Asian carp genetic material, and is certainly not as conclusive as the presence of live or dead fish.
When the positive eDNA showed up in the water samples from the Muskingum, it told the scientists who have been Sherlock Holmes-ing for years on the trail of these pests that Asian carp could be present in the waterway, which feeds into the Mississippi River system via the Ohio River.
But after what was labeled as an “extensive” search, with electrofishing crews attempting to shock up Asian carp at 125 sites along the length of the Muskingum, and in sections of the Walhonding and Tuscarawas rivers which drain into the Muskingum, only a few grass carp were found — not the notorious and most troubling bighead.
“Asian carp” is the collective term for the four exotic species that present various levels of threat to the waters of the Great Lakes — the bighead, silver, grass, and black carp.
Bighead and silver carp were imported in the 1970s in a cost-saving effort to control algae in catfish farms in Arkansas, but they reached the Mississippi River system either by escaping those facilities during floods, or by accidental introduction. These two species have been on a relentless charge throughout the watershed ever since, and are considered the most prolific and the most destructive species of Asian carp.
Grass carp consume aquatic vegetation and destroy habitat used by native fish, while black carp eat snails and mussels and are a threat to those species. Some grass carp were found in the search along the Muskingum, and they could have escaped from ponds during periods of flooding. Ohio is one of 43 states that permits the sale of sterile grass carp to private pond owners to help control vegetation. Bringing fertile grass carp into the state has been outlawed since 1988.
Bighead and silver carp are filter feeders that devour massive amounts of plankton, depleting the food sources for native fish. They thrive in nutrient rich waters, such as those found in the Muskingum River system and in western Lake Erie. It is illegal under federal law to bring bighead or silver carp into Ohio.
Darrell Gibbons, who has operated the D&D Bait and Tackle shop near the Muskingum River in Zanesville for the last 18 years, said there are dozens of streams, ditches, and creeks that make their way to the Muskingum, so locating individual fish would be comparable to finding that lone needle in the haystack.
“I’d say it’ll be tough finding them, especially if we’re just talking about a few fish, since there’s quite a lot of streams they could run up. They could be anywhere,” he said. “If the Asian carp do get in, I can see them maybe hurting the bass and crappie populations here. We’re mostly fishing for flathead catfish, and I don’t think they’d be hurt too much.”
Rich Carter, the executive administrator for fish management and research for the Ohio Department of Natural Resources’ Division of Wildlife, said the electrofishing took place in June and July, and was conducted by ODNR staff. The fact the search did not turn up any Asian carp in the Muskingum is a blessing that carries with it a seemingly permanent caveat.
“We’re encouraged with the recent sampling results, however, we know we need to continue to be vigilant in looking for Asian carp in the Muskingum River,” Carter said, “because of the connections that river system has with potential pathways to Lake Erie.”
The Muskingum River is a flashpoint in the battle to keep Asian carp out of the Great Lakes since its headwaters have two potential connections to Lake Erie — one along Little Killbuck Creek in an agricultural area, and another where a section of the Ohio-Erie Canal bridges two watersheds. The U.S. Army Corps of Engineers cited these as potential pathways the Asian carp could utilize to slip from the Mississippi River basin into the Lake Erie watershed.
When the eDNA detection turned up positive hits for bighead carp, the closest one to Little Killbuck Creek was approximately 100 river miles away, while the nearest sample from the Ohio-Erie Canal connection was about 120 river miles away.
Bighead and silver carp now dominate large stretches of the Missouri, Mississippi, and Illinois rivers, and in some cases make up 80-90 percent of the fish in certain areas. Their primary access route to the Great Lakes would be through the Chicago Sanitary and Ship Canal, a man-made link between the Mississippi Watershed and Lake Michigan. An electrical barrier operated by the U.S. Army Corps of Engineers about 25 miles from the lake is supposed to keep them out, but many have questioned its reliability.
Contact Blade outdoors editor Matt Markey at: firstname.lastname@example.org or 419-724-6068.
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