Mild winter likely set stage for Lake Traverse fish kill

Mar. 19—BROWNS VALLEY — An early analysis of the recent fish kill on

indicates that the mild winter weather likely set the stage for it.

An affliction known as "gas supersaturation trauma" is the preliminary diagnosis for the fish kill reported March 14, according to Ortonville Area Fisheries Supervisor Chris Domeier with the

.

He estimates that there were 2,000 to 3,000 dead freshwater drum or sheepshead, and several hundred each of dead crappies, bluegills, catfish and white bass when he boated the affected area of the lake. He estimates there were also around 100 each of dead walleye and smallmouth bass.

Domeier and fisheries staff conducted a field investigation, collected water data, photographed and sampled fish.

Dr. Isaiah Tolo of the Minnesota DNR fish health laboratory analyzed the data. He concluded that gas supersaturation trauma, also known as gas bubble disease, is likely the cause of the kill.

It results when there is a supersaturation of oxygen and other gases in the lake.

"Under these conditions the dissolved gases in the blood and tissues of exposed fish can come out of solution and form gas emboli (gas bubbles) leading to various health issues, such as heart or kidney failure, and can ultimately kill a large number of fish," Domeier wrote in a synopsis of the finding.

He added that fish have been submitted to the laboratory for a confirmation of the diagnosis.

The mild winter, sunny days and thin, clear ice provided good conditions for algae to grow in the lake. The heavy algae growth can lead to the higher-than-normal levels of oxygen and other gases in the lake, Domeier explained.

While the fish kill will affect the number of freshwater drum, bluegills and crappies available to anglers, Domeier believes that overall the lake should still provide decent fishing opportunities this coming season.

The shallow lake covers 10,848 acres in Traverse County on the Minnesota border with South Dakota.