Fish Kills at Johnson Lake

Recently a number of dead fish have appeared at Johnson Lake.  To the cabin owner it can be unsightly – and smelly — around their dock or shoreline; to the angler it is a lost recreational opportunity. For a biologist, it generally means something, ecologically, has gone wrong.

At Johnson Lake, the majority of the dead fish have been freshwater drum.  Over the past several years, these kills have become a common occurrence.

Experts with the Nebraska Game & Parks can’t identify the exact reasoning for the number of freshwater drum found dead, but they attribute it mostly to the rapidly rising water temperatures, dissolved oxygen issues in the water or even problems associated with harmful algal bloom.

The warmer the weather, the less oxygen the water can hold.  Additionally, fish require more oxygen to survive in warmer water than they do in cold water because their metabolism is higher.  All these factors contribute to the fish getting stressed as they try to adapt to the changing environment.  Freshwater drum are bottom dwelling fish so when the water warms up at lower depths, the fish aren’t able to extract sufficient oxygen from the water.

Any cabin owner or fisherman with further questions should reach out to the local Nebraska Game & Parks office with any fish-related concern or the Nebraska Department of Environmental Energy with any water quality concerns.