Dead fish lined the banks of a popular fishing spot along Swan Creek Sunday as the Ohio Department of Natural Resources investigated a large fish kill numbering in the tens of thousands in a roughly two-mile area near Highland Park.
The cause of the deaths was unclear.
"We don't have a source yet, and that's what we're trying to find," said Bob Radcliff, a wildlife officer supervisor with the ODNR's Division of Wildlife.
Oxygen depletion in the water caused the fish to drown, but what caused the oxygen level to fall was unknown, Mr. Radcliff said.
The acidity balance and water clarity were good, and the creek appears to be an otherwise healthy ecosystem with large-sized bass and pike found among the dead fish, Mr. Radcliff said.
Several ODNR officers waded in the water counting the fish, and Toledo Environmental Services tested the water to help identify the source of the problem, Mr. Radcliff said. They will be back today to continue the investigation, he said.
Several neighbors are concerned about what caused the fish to die.
Jason Gorr, a member of the Highland Park Neighbors Association who is an unofficial resident wildlife expert, was in shock as he looked at the fish along the water's
"They're all over the place," he said. "I've never seen anything like this before. It's awful."
It's particularly upsetting that this would happen while there is an effort to clean up the area, he said.
Last year, the Highland Park Dam was replaced with a fish-ladder to stop the impediment to passage of many fish species along the creek, which feeds into the Maumee River.
A variety of fish species were found along the banks, including perch, pike, bass, sheephead, gobies, and sunfish. Most of the fish were smaller, but state investigators found bass and pike that were more than a foot long, Mr. Radcliff said.
Chuck Childers lives on Finch Street within walking distance of the park.
"I could see dead fish floating downstream," he said. "I really want to know how this happened."
The ODNR officers on scene said they have been called to fish kills in Swan Creek before, but this was the worst they've seen in years.