Seeing Thousands of Dead Fish in Louisiana? Here’s Why

Summer heat isn't just rough on us, it's frequently just as tough on fish in our Louisiana waters.

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Though summer won't officially arrive until June 21, the the Louisiana Department of Wildlife and Fisheries is already reminding everyone that increased water temperatures, storms, and extended cloudy weather can lead to fish kills in inland and nearshore waters across the state.

READ MORE: LDWF Stocks Thousands of Florida Bass Into Several Local Lakes

These events are typically caused by low dissolved oxygen (hypoxia), which often occurs in warm water, since it has a lower carrying capacity for oxygen than cooler water. Conditions such as stagnant water, heavy rainfall, decaying vegetation, or increased nutrient runoff contribute to hypoxic conditions—especially in shallow bayous, marshes, and ponds.

Fish kills may affect certain species or sizes more than others. For example, shad are sensitive to hypoxia, and are often the first or only fish that experience a fish kill, while some species, like gar, can breathe air and are resistant to hypoxic conditions. Other species have varying levels of tolerance to hypoxic conditions.

How Does A Fish Kill Happen?

There are a number of reasons for massive fish kills this time of year, including chemical spills and algae blooms, but the number one killer is low oxygen levels in the water due to high temperatures.

In this video from the Australian Academy of Science, we get a better picture of what's going on.

It's Best Not To Eat The Fish Dying From A Fish Kill

For those who have witnessed a fish kill, seeing hundreds, if not thousands, of dead or dying fish, is pretty disturbing. LDWF Inland Fisheries Technical Advisor Robby Maxwell says, “When people usually see fish kills, the fish are usually bloated, you see them gasping and they’re floating on the top and they are starting to rot. I generally wouldn’t eat them. There always is a chance that it could be related to pollution, spill, or something else.”

Should you happen to witness a fish kill, LDWF asks that you report it immediately. “If you see dead fish in public waters please report them. Call your local district fisheries office and just report what you’re seeing, where you are and how many dead fish there are and we will respond to it in an appropriate manner.”

Just go to the special "fish kill" page on the LDWF website.

While fish kills can temporarily impact recreational and commercial fishing, aquatic ecosystems in Louisiana are resilient and typically recover naturally. Even in large fish kills, some fish will find refuge from hypoxic conditions in the affected waterbody or connected waterbodies and survive. Scavengers and decomposers help break down fish remains, and most systems recover over time.

If conditions remain favorable, fish populations often rebound after major kills within one to two years without the need for stocking, and young fish benefit from reduced competition and increased resources. However, fish kills caused by pollution or chemical spills can occur at any time and may require additional response.