To Anglers’ And Boaters’ Delight, Giant Salvinia Is Gone From Two Texas Lakes … For Now

The invasive plant that grows in dense green clumps crowds out the freshwater habitats of native plants and animals.

By Michael MarksMay 3, 2019 12:02 pm,

Giant salvinia is a menace. It’s a plant that grows in dense green clumps on top of bodies of fresh water in Texas. But it’s not native to the state; it’s originally from South America, but people brought it here to put into aquariums. But now it’s in the wild, and it crowds out native plants and animal habitats – it can often double in size in just a week. That rapid pace of replication means eradication is nearly impossible for most lakes. But Lake Fork outside of Dallas is different.

The lake is a destination for those who are looking to catch a big fish, at least according to Michael Rogge who moved there in 1993 to start a fishing guide business. Now, he’s president of the local chamber of commerce, which essentially makes him the lake’s biggest cheerleader.

“If you want the fish of a lifetime, you come to Lake Fork,” Rogge says.

Rogge’s busy and doesn’t have much time to talk. That’s because this weekend, Lake Fork will host a Bassmaster Elite Series tournament, a competition that pays out $100,000 to the first-place angler. Rogge has been swamped, helping with the last-minute logistics. He doesn’t mind though; the community’s economy depends on fishing tournaments like this, and it’s the kind of thing a giant salvinia infestation would have prevented.

“It would be catastrophic if it got out of hand because we depend a lot on people coming from all over the world to fish this lake,” Rogge says.

In addition to pushing out other plants and wildlife, salvinia can grow so thick on top of the water that a boat or a fish hook can’t get through it. For a while, it looked like that might happen on Lake Fork; patches of the plant lingered on the lake for years. But this week, the Texas Parks and Wildlife announced that it was gone from Lake Fork, as well as from Lake Athens, about 70 miles south. It was an uncommon piece of good news that John Findeisin was happy to talk about.

“Eradications: while they do happen, they are rare,” Findeisin says.

Findeisin is an an aquatic invasive species specialist with Parks and Wildlife. He says containment is usually the best he can hope for.

“Being able to eradicate the salvinia on both of these is a huge victory for us because it shows that we can do it,” he says.

The infestations on both Lake Fork and Lake Athens covered just a few dozen acres at their peak – nothing to sneeze at, but small compared to Caddo Lake, for example, where salvinia blanketed more than 6,000 acres. For over a year, Findeisin and others isolated the salvinia on Fork and Athens, and then experimented with different combinations of herbicides. They made some progress, but the biggest boost came from Mother Nature.

“In, I believe it was January of 2018, we had a really, really cold snap; it stayed below freezing for three or four days straight. And that had a greater impact on the salvinia than what we ever did,” Findeisin says.

There was some good fortune involved but Findeisin still considers it a win. The wins are rare in his business, and getting rid of even a small infestation lowers the risk of the plant spreading to other lakes. Still, salvinia has a habit of stowing away on outboard motors and trailers, so Findeisin says boaters should be extra careful not to carry it to other bodies of water. Even though salvinia is gone from Lake Fork and Lake Athens now, that doesn’t mean it can’t come back.