Observant visitors of DeWitt Recreation Area and the adjacent pond have noticed an unusually large number of fish this year; however, instead of swimming around, they were dead.

One person, who labeled herself “a concerned citizen,” said that while walking around the trail, “I saw a massive amount of dead fish, more than I have ever seen in the spring (well over 60),” she said. “And the DEC was there testing. I am worried something is wrong with the water. I know it’s a run-off for quite a bit, and people eat the fish.”

Another reader of The Batavian submitted photos of the finned creatures that were spotted floating on top of the edge of DeWitt Pond on Cedar Street in Batavia.

The Batavian reached out to Department of Public Works Commissioner Tim Hens for answers as to why fish are dying and the possible connection to the water quality and the state Department of Environmental Conservation’s recent visit.

“Genesee County Parks Staff is aware of the dead fish at DeWitt Pond. Most appear to be carp. This appears to be a normal winter die-off. The low lake levels and extreme ice thickness likely contributed to the higher seasonal die-off from low oxygen levels in the water,” Hens said. “The DEC is currently getting ready to stock the pond with Brown Trout on April 1. In an abundance of caution, we have reached out to them regarding the fish die-off. We have not heard back from them yet.”

An article on “Winterkill in Ponds” at Penn State University’s Extension website, explains it this way:

Winterkill refers to the loss of fish in winter because oxygen is lacking in the pond. Submerged vegetation and algae create oxygen through the process of photosynthesis. During the winter, oxygen production is often reduced because ice and snow on the lake limit sunlight reaching vegetation. In small, shallow lakes, the available oxygen can quickly be used up by live plants and fish that consume oxygen in the evening, and by bacteria that feed on dead and decaying vegetation. When the oxygen level declines, less tolerant fish species (such as carp) and fish in poor condition overall can begin to suffocate.

Oxygen enters ponds by moving from the air into the water aided by the wind, or from photosynthesis by the plants in the pond. Ice cover blocks oxygen movement from the air into the water, and oxygen produced by algae and plants become the only source. Thin, clear ice allows oxygen production by plants and algae since enough sunlight can filter through the ice to allow photosynthesis. If the ice remains into mid-winter or thickens slightly, oxygen levels will begin to decrease because each day, pond plants and animals use oxygen, even in winter, as the animals breathe and dead plant material decays.

Conversely, the more water volume there is in a pond, the less likely the pond will experience winterkill.

Updates from the DEC will be reported by The Batavian about any water or other issues related to the dying fish other than what Hens suspects is the reason.