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HOOKED ON EAST TEXAS: Battling Giant salvinia at Caddo Lake

Biologists are taking a two-pronged approach in an effort to control an invasive species.

TYLER, Texas — Invasive species -- it sounds troublesome and it is, especially on one East Texas lake. But Texas Parks and Wildlife Department (TPWD) biologists are getting to the root of the problem with a two-pronged approach. 

Biologist Tim Bister showed CBS19 what biologists are battling: a water plant called Giant salvinia. Giant salvinia is a fuzzy, hairy, floating aquatic fern. It’s from South America, but not welcome on Caddo Lake. 

Bister said the invasive species got here on boat trailers.

We took a trip with Bister and fellow biologist Thomas Decker to areas of Caddo Lake where Giant salvinia has been a challenge to control. A few years ago, half of the Texas side of Caddo Lake was covered with thick mats of salvinia. 

The TPWD is fighting back by using an herbicide, which kills the plants but doesn't harm fish. That's important on Caddo Lake because bass fishing is big business in this part of East Texas. It's also important to control the Giant salvinia, not just on Caddo, but on up to three dozen lakes across Texas. 

Decker said it takes constant effort. 

“It’s one of these plants that if you take your eye off of it for just a just a little bit and you think you’ve got it killed or got it under control you can come back and it’s out of control again,” Decker said.

And if Giant salvinia gets out of control, it can prevent native plants from growing underneath. Why? Remember science class and a process called photosynthesis? 

“If you don’t have sunlight getting into the water," Bister said. "Plants aren't getting oxygen, then you have lower oxygen levels underneath the thick mats. Fish don’t like it. It just creates a real problem."

The TPWD is getting help fighting Giant salvinia from a local citizens group called the Caddo Bio-Alliance (CBA). The CBA is helping with the biological control aspect of fighting Giant salvinia. They are growing weevils, tiny insects that eat the plants.  

The biological control and the herbicide spraying are working but Bister said he's not sure Giant salvinia will every be eradicated. The goal is for people to be able to use the lake as they want to.

"We’re never going to get rid of this invasive species here but we’re learning how to control it," Bister said.

And you can help control and stop the spread of invasive species. The TPWD asks that those who use Texas waterways to clean, drain and dry their boat, trailer and gear every time they leave a body of water.

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