Algae, excessive heat blamed after hundreds of fish turn up dead in pond at Cherokee Park

LOUISVILLE, Ky. (WDRB) -- Excessive heat is one of the factors that led to the deaths of hundreds of fish in a pond at a popular Louisville park.

The dead fish began surfacing in Cherokee Park's Willow Pond this week, coinciding with a heat wave that has scorched Louisville for several days.

A fisheries program coordinator visited the pond earlier this week and observed several dead bass, bluegill, catfish and carp floating on the water's surface.

Dane Balsman, an urban fisheries biologist with Kentucky Department of Fish and Wildlife, said Wednesday that a combination of factors caused the oxygen to be depleted from the water.

"There was a pretty substantial fish kill," Balsman said. "... The fish didn't get enough oxygen, and it killed a lot of the fish there.

"What happened was there was probably a large algae bloom a few days ago. We had a couple of cloudy days late last week. All that algae decomposed at the same time, causing the oxygen depletion. When it decomposes at the same time it uses up all the oxygen in the water, and the fish didn't have enough oxygen."

Balsman said the heat made the situation even more lethal.

"This hot weather didn't help either," he said. "The fish need a lot more oxygen when it gets hot like this. Their metabolism picks up the hotter it gets, and they need more oxygen."

Balsman said all species of fish were affected, including bass, carp, catfish and others.

Algae blooms are usually not a problem, Balsman said, unless it begins to decompose at the same time.

As for the fish that are decomposing in the water, Balsman said they should be gone within a few days, and they pose no health risks.

"It's going to be a few days," Balsman said. "This weather's hot, they'll decompose pretty quick. It doesn't pose a risk for other fish in the pond. So it'll be kind of a stinky mess here the next couple of days. But that'll decompose, the fish will break down. Turtles will eat them, vultures will eat them. So it will go through the food web that way - a natural process."

Not all fish were killed, and there are still healthy fish in the water. Balsman said it is safe to fish, and a few people were casting lines Wednesday afternoon.

On Tuesday, Nathan Brooks, a fisheries coordinator, pointed out that it's always up to the person catching the fish to decide whether or not they want to eat it.

"There is no expectation that it is unsafe to fish or consume what is caught," Brooks said. "No matter what body of water someone fishes, consuming the fish they caught is a personal decision with varying factors."