Thanks to a grant from the city of Marshall, and the investment and efforts of Marshall native John Sanders, the Caddo Lake Institute recently was able to participate in mechanical harvester trials to evaluate whether physical removal can play a significant role in the management of invasive aquatic vegetation at Caddo Lake.
By Jack Canson, Caddo Lake Institute, Mechanical Harvesting Project Director
Thanks to a grant from the city of Marshall, and the investment and efforts of Marshall native John Sanders, the Caddo Lake Institute recently was able to participate in mechanical harvester trials to evaluate whether physical removal can play a significant role in the management of invasive aquatic vegetation at Caddo Lake.
Although it will be a month before the data obtained from these trials can be analyzed and evaluated, several important observations have been made by many who saw the harvesting equipment in action.
Foremost among these is this: mechanical harvesting machinery can operate in Caddo Lake's shallow, stumpy waters.
In the past, those who have inquired about harvesters at Caddo Lake have often been told that machines had been tried but always broke down within hours. We recently concluded 80 hours of on-water harvesting without losing a single minute to operational difficulties of any kind. The harvester hit many stumps without breaking down.
Another apparent benefit of harvesting is that mechanical removal of aquatic vegetation can provide immediate relief to anglers and recreational boaters, and immediate benefits to marina and fishing camp operators.
Our ten-day test occurred near Tucker's Camp, a popular spot on the southwestern corner of the lake near Long Point.
Before the harvester began operating, the major east-west boat road connecting Tucker's to the rest of the lake was impassable to most boats. The area between Tucker's Camp and Bird Island, well-known for its bream beds and excellent fishing overall, was a solid carpet of vegetation. In one week's time, the harvester removed several hundred thousand pounds of aquatic plants from there, creating open water where it has been clogged all year. This particular area is of importance to many people who don't own boats and motors because, when the water is open, they can rent a small boat from Mrs. Tucker and paddle out for good fishing.
Whether large scale mechanical harvesting at Caddo Lake is a viable option remains to be seen. Measurements and observations recorded during the trial will help us develop a cost/benefit analysis that will, we hope, be useful to decision makers in the various agencies and organizations on both sides of the lake.
Obviously, mechanical harvesting is more labor intensive and time consuming than herbicide applications using airboats – and, thus, more expensive. Harvesting, however, creates other values. One of the objectives of the trials just concluded is to obtain a better understanding of the value of removing an acre of vegetation from the lake versus the value of an acre of vegetation killed by herbicide and left in the lake.
Most people involved with aquatic vegetation control don't regard mechanical harvesting versus chemical treatment as an either-or situation. Along with prevention, containment, chemical, and biological measures, harvesting is another tool for lake management. We think it is an important one because removing vegetation from the lake removes the nutrients that encourage more vegetation growth and partially decomposed vegetation adds to bottom-filling silt.
Among those who visited the trial were two elected officials whose support for adding a harvesting component to Caddo is essential — U.S. Representative Louie Gohmert and County Judge Richard Anderson. To continue harvesting, federal support is needed. To make an integrated herbicide and harvesting program work, we will need the same kind of self-help attitude that created the Cypress Valley Navigation District Spray Team that Judge Anderson, CVND Chairman Ken Shaw, and North East Texas Municipal Water District Manager Walt Sears were instrumental in invigorating.
"That harvester was a great investment, and it is wonderful to see the city of Marshall and Caddo Lake working together to do something so visibly helpful to the lake's health," Rep. Gohmert said.
"I'm hoping Caddo can become an incubator for ways to manage invasive species that can completely choke and kill a lake, then use those techniques to save other lakes across the country."
Judge Anderson also reviewed the harvesting trials in positive terms.
"I was very impressed with the harvesting project," he said. "
During the last two years, volunteers have joined with local governments, non-governmental organizations and private foundations in the fight against giant salvinia. The efforts of John Sanders, and other interested individuals, provided a 'proof of concept' that mechanical harvesting is feasible and can be utilized along with herbicide, the weevils, and other potential biologicals to mount a more effective attack on the salvinia problem."
The harvester trial project would not have been possible without the help and assistance of Texas Parks and Wildlife officials in our area and in Austin. Fisheries biologist Tim Bister assisted in developing the treatment proposal and surveyed the lake to recommend areas in which to operate the trials. Howard Elder, TPWD's aquatic habitat biologist, also provided encouragement and guidance. Other support from the U.S. Fish & Wildlife Foundation made this project and the evaluation possible.
My thanks especially goes to the people of Marshall and to Marshall City Commission Chairman William "Buddy" Power, and Commissioners Wilborn, Hoffman, Timmins, Hester, Paddie, and Moon. Without their enthusiastic and unanimous support, mechanical harvesting would still be waiting to take the first step.
Lively discussion, even arguments, about the values of herbicide treatments versus mechanical removal will continue for as long as invasive aquatic vegetation problems exist.
But at Caddo Lake we now have first-hand experience with harvesting equipment, and we've obtained information and data that will elevate those discussions from matters of opinion to testable ideas based on observable facts.
