Heat, storms, cause fish kills in south, central Louisiana

June 16, 2022 GMT

BATON ROUGE, La. (AP) — Heat and storms are contributing to “a rash of fish kills” in south and central Louisiana, and more are likely, the Louisiana Department of Wildlife and Fisheries said Thursday.

“While fish kills are shocking to experience and can appear devastating,” they aren’t an ecological problem, a news release said.

“Heat- and storm-related fish kills have occurred in Louisiana since before recorded history, and the ecosystems have evolved to be resilient and bounce back from them,” department spokesperson Rene LeBreton wrote.

As water heats up, it loses capacity for holding dissolved oxygen. Stagnant water, decaying plants, a long stretch of cloudy weather, and runoff laden with sediment or nutrients can also reduce the amount of available oxygen.

In addition to creating runoff, thunderstorms can mix low-oxygen water at the bottom of a waterway into upper layers, reducing the oxygen there.


Because different species and sizes of fish may require different amounts of oxygen, sometimes only some are killed. In addition, many fish and aquatic animals can swim into fresher waters.

“Decomposers and scavengers, including microbes, crawfish, crabs, fish, alligators, turtles, raccoons, and birds, will do their part in helping to clean up fish carcasses,” LeBreton wrote. And, with fewer predators and more resources available next spring, a “boom year of reproduction ... will surely follow.”

He said fish kills “often lead to a rejuvenated system that is healthy and naturally replenished in the following years.”