Photo by David Slone, Times-Union

Pictured are some of the hundreds of dead gizzard shad along the Pike Lake shoreline. The dead fish could be found Thursday from Beyer Park to just past the bridge before the beach.
Photo by David Slone, Times-Union Pictured are some of the hundreds of dead gizzard shad along the Pike Lake shoreline. The dead fish could be found Thursday from Beyer Park to just past the bridge before the beach.
Hundreds of dead fish laid along the shoreline of Pike Lake Thursday, from Beyer Park to the bridge just before the beach.

The gizzard shad were in various stages of decay.

The cause? Likely the harsh winter.

Information provided by Lilly Center for Lakes and Streams Director Dr. Nate Bosch states that “ice cover alters the lake environment by insulating and shading the lake and forming a seal that stops oxygen transfer between the air and water.

“Through the winter months, oxygen in the water is continually being used up through the process of decomposition of dead plant material. This decline in oxygen is made worse if there were too many nutrients in the lake in previous seasons. That’s because more nutrients lead to more plant material accumulating at the bottom of the lake, which means there is more material that will use up oxygen as it decomposes.

“Since the ice seals off the oxygen, the lake only has a limited amount before it runs out. This has important implications for fish. Most fish reduce their activity during the winter months, but the fish still rely on oxygen in the water to breathe. If oxygen runs out under the ice, fish kills will result.”

After the ice melts, the dead fish then float to the surface and end up wherever the wind and waves take them, often in the same area of the lake.

Due to the cold water temperatures, the fish may not decompose at the same rate.

All varieties of fish can be affected by low oxygen levels.

Bosch said if all the fish are the same species, that could indicate a virus. However, he said the gizzard shad are more susceptible to a winter fish kill because here they are on the northern edge of their habitat. The Center has received reports of dead shad on Winona Lake and the Barbee Lake chains, too.

“They bounce back pretty quickly,” he said.

Gizzard shad are a deep bodied fish that are nearly flat when lying on their side, according to the Ohio Department of Natural Resources Division of Wildlife website. They have a bright silver body with slate gray fins. There is a dark spot just behind the gill openings on the upper sides. They have a small sub-terminal mouth that does not extend much beyond the front edge of the eye. The dorsal fin is positioned directly above the pelvic fins and have a greatly extended last dorsal ray that extends about as far back as the center of the anal fin. Their belly comes to a point with a single row of scales folded over the edge.

An adult typically measures 10 to 15 inches in length, but can reach 20 inches, and usually weighs 1 pound or less, but can reach 3.5 pounds, the website states.