Aquatic Plant Management Program Enhancements
The FWC is committed to implementing a variety of enhancements to the Agency’s Aquatic Plant Management Program. Some of these improvements include exploring ways to better integrate and increase the strategic use of mechanical aquatic plant harvesting and creating habitat management plans to guide efforts for individual lakes.
The FWC created a Statewide Technical Assistance Group, or TAG, to address the many challenges and issues associated with aquatic plant management in Florida. The Aquatic Plant Management TAG will provide a forum for discussion on all aspects of the aquatic plant management program. The goal of the TAG is to establish areas of common ground, identify problems, concerns, and areas of disagreement, evaluate scientific information, develop potential solutions to identified problems and provide a useful forum for sharing information and ideas.
Nearly 30 individuals representing both recreational and professional anglers, waterfowl hunters, water-related businesses including restaurants and marinas, recreational groups, conservation organizations, local governments and partner agencies have joined the TAG.
The first TAG meeting was held in September of 2019. The group is currently planning to meet 4 times a year.
The FWC is working to explore new methods and technologies to oversee and increase accountability of aquatic plant control contractors, including a real-time tracking system that monitors contractors and records precise locations of herbicide applications. This fleet tracker technology, similar to systems used by shipping and trucking companies is being tested on Lake Okeechobee with the goal of having this type of technology a requirement of the new contracts for aquatic plant control contractors. Once installed the trackers will show precise routes of all equipped vessels including the locations where herbicides were applied.
The FWC uses mechanical harvesters all over the state. Currently we are investigating ways to increase our use of mechanical harvesting.
Mechanical harvesting refers to the use of machinery to remove, convey and transport aquatic plants and associated organic material to in-lake or upland disposal sites. Mechanical shredding involves machinery designed to cut and shred aquatic plants into much smaller pieces allowing them to sink to the bottom of the waterbody. Mechanical controls range from small cutting boats to 90-foot long harvesters, and from track hoes and draglines stationed on shore or mounted on barges that lift plants and debris out of the water.
Mechanical harvesters are one method of controlling nuisance and invasive vegetation. One advantage of mechanical removal is there are no restrictions on water use following a treatment as there sometimes are with chemical treatment methods. Mechanical harvesters do increase water turbidity, but that is a temporary impact. While some small fish, amphibians, reptiles and invertebrates are removed as unintended by-catch, there is no evidence this will significantly affect over-all populations. Removal of the plant biomass prevents its eventual decay and settling to the bottom, helping to reduce sedimentation in the lake. Also, there is some level of nutrient removal with harvesting too, because the nitrogen and phosphorous that is bound up in the plant is removed from the water body.
However, mechanical harvesters alone cannot keep pace with the exponential growth of invasive aquatic plants in Florida waters. Resource managers in Florida and throughout the U.S. rely on an integrated approach to control invasive plants including herbicides, biological agents such as grass carp and sometimes even manual removal such as hand pulling.
In an effort to find new ideas for managing aquatic plants without the use of herbicides, in December of 2019 the agency posted a Request for Information soliciting innovative ideas from those in the plant management industry, scientific experts and the general public. The FWC along with outside partners reviewed these submissions. Although there were a few conceptual ideas staff and partners would like to see when they are further along in development, reviewers did not identify any proposals for available technologies not already being used in the state program. However, the FWC did receive some information which may help staff with better procurements for some mechanical control services. To ensure any new technologies are not overlooked, the FWC is in the process of letting a Request for Proposal for an independent, international environmental consulting company to look at the FWC’s program as well as the aquatic plant management programs of other states and countries to see if additional technologies from around the world could be used. Check back for updates on this process.
The FWC has been working to improve the timing of herbicide-based management activities so as not to interfere with important recreational opportunities such as waterfowl seasons and fishing tournaments. Staff work to ensure that herbicide treatments on lakes heavily used for duck hunting is minimal, or not done at all during hunting season. Staff also plan around fishing tournaments so as not to interfere with the event.
Public feedback received by the FWC indicates people would like to see more contractor oversight. Therefore, staff began to research systems that track herbicide application and started testing on an ‘off the shelf’ system. Unfortunately, the testing indicated this system is too complicated and error prone to provide a dataset reliable enough for oversight.
During the testing period with this equipment, staff undertook a separate project, partnering with the University of Florida, on Lake Tohopekaliga to evaluate aquatic plant harvesters. The lead UF researcher for that project was using a GPS system that reported data remotely using a 4G cellular card. FWC staff were able to reconfigure the harvester system to create a new system that would also work during aquatic plant spraying activities. The system is wired to a component on the applicators’ spray rig that indicates when there is liquid flowing or when there is no liquid flowing. With this setup, the boat operator never has to remember to turn anything on or off; when the boat ignition is engaged, the GPS starts recording automatically, including when the spray nozzle is engaged.
This system worked well and gave staff a track of where applicators went and exactly where plant control was conducted. The FWC purchased additional GPS units to pilot this technology on all contractor boats working for the FWC on Lake Okeechobee. The pilot program is going well, and our goal is to expand to all of our contractors throughout the state when our contracts renew in 2021.