Discovery of salvinia on Fork and Palestine is not good news

Published on Saturday, 25 November 2017 02:18 - Written by STEVE KNIGHT/

Summer fishing ended with a bang in Northeast Texas. Well maybe it was more of an explosion, and not in a good way.

As October turned to November, reports came in from both Lake Fork and Lake Palestine of giant salvinia infestations, followed by confirmed sightings of zebra mussels on Richland-Chambers Reservoir and Lake Livingston.

Giant salvinia reports are nothing new on either lake, but in both cases this is the largest amount found on either. It could also be the beginning of an ongoing problem.

It is believed the infestation on Lake Fork covered about 10 to 15 acres. At Palestine it was initially thought there was also about 10 acres of the invasive plant, but two weeks ago another patch totaling about 20 acres was discovered and TPWD employees were still finding more.

It is believed that the giant salvinia had been on Lake Fork for eight to 10 months and maybe as long as a year on Palestine. It was possibly not reported sooner because boaters initially thought it was duckweed.

Kevin Storey, Texas Parks and Wildlife Department Inland Fisheries District biologist for Fork, said that a Sabine River Authority employee discovered a patch covering about 10 acres in White Oak Bay in late October.

‘There is a private ramp in the back of the cove that belongs to a homeowner’s association back there. That’s likely where it was introduced,” Storey said.

After the first discovery, SRA officials continued searching the lake and found more along the Farm-to-Market 17 bridge at the Fisherman’s Cove ramp.

Containment booms were installed at the two sites and crews using a mixture of contact herbicide and systemic herbicide sprayed the areas.

“These two new infestations are too far apart to be related and it’s inconceivable they are also related to the trouble we had in Chaney Branch,” Storey said.

Fishermen discovered patches of giant salvinia in Chaney Branch and another small cove west of the dam in November 2015. It is believed that spray treatments were successful in eliminating those patches.

At Palestine, the first patch of giant salvinia was found in Saline Bay above the FM 344 bridge in September by a TPWD employee bowfishing. A second patch was discovered recently west of the FM 315 bridge in Kickapoo Creek.

TPWD biologist Richard Ott said about 20 acres of salvinia was found in Saline Bay. He added the amount in Kickapoo was much smaller, but as the search continued a week ago more was being found.

“Previous locations for Lake Palestine were at the FM 315 ramp and at Villages Marina. Both of those locations were cleared many years ago. The new infestation above 315 is likely not an expansion of the earlier infestation because it has been too long ago. The 315 location is popular with duck hunters but obviously this would just be corollary not evidential,” Ott said.

Spray efforts at an average cost of $50 per acre have already been conducted at both locations.

First discovered on Toledo Bend in 1998, there are current infestations on Toledo Bend, Sam Rayburn and Caddo Lake.

The concern with giant salvinia is not to water quality but to boater access and aquatic life. During the growing season the invasive South American plant can double in volume weekly. It grows in a floating mat that can eliminate boating traffic for everything except airboats. Thick patches will also reduce oxygen, making it impossible for fish species to live under it. In the shallow Caddo Lake, large areas on the Texas side have not been navigable for years. On Toledo Bend and Rayburn where the water is deeper, salvinia problems come and go in the backs of coves and shallow creeks.

“Giant salvinia has no redeeming qualities. Period,” Storey said.

Asked if the spray effort will eradicate the giant salvinia on the two lakes, John Findeisen, TPWD’s Brookeland Aquatic Invasive Species team lead, was not optimistic.

“The short answer is no. There is too much out there to treat every individual plant, some of it is mixed in with other vegetation, and some of the mats are several layers thick. We are only treating the open mats of salvinia on Lake Fork and Palestine. The open mats are more numerous at Lake Palestine,” Findeisen said.

The biologist said minus extreme cold weather this winter, the plant likely would thrive in the backwaters in coves where there is little wind and wave action. This could especially create problems throughout Kickapoo Creek and the upper Neches River channel on Lake Palestine.

He explained that through experience they have learned that attempting to treat both giant salvinia along with other vegetation made matters worse.

“The salvinia would rebound faster than the other plants and create one huge giant salvinia mat. This mat then moved around easily with the lightest wind or water current and has spread the plant almost lake-wide,” Findeisen explained.

The new plan is to treat large mats with chemicals and use salvinia weevils, existing vegetation and hopefully a cold winter where salvinia is mixed with other vegetation.

Both Storey and Ott agree that fishermen and duck hunters need to be diligent about cleaning their boats and trailers before moving from one lake to another so they don’t transport the plant.

Spring and fall is the best time for the plant to successfully be moved from one lake to another because it can survive out of water longer. If it is spotted on the water, the best thing to do is to call local TPWD fisheries biologists as soon as possible.

“Despite our efforts to make boaters sensitive to the issue, there are still many people who don’t know what giant salvinia looks like. It does not take much effort to search for images on your smartphone. We’d prefer if anglers see something suspicious that they contact us and text us a picture so we can confirm its identification. We’ve heard numerous people confuse water hyacinth with giant salvinia. Waiting for six months before an issue is reported gives the plant too much time to establish itself,” Storey said.