Florida's outstanding freshwater fisheries are heavily dependent on natural aquatic vegetation. Aquatic plants provide the following benefits:

• cover for young fish to hide from predators,
• food for many insects that fish eat,
• protection from currents and silt for fish eggs in spawning nests , and
• structure which sportfish use for shade and camouflage, which in turn helps anglers locate them.

On the other hand, some aquatic plants that are not native to Florida have a competitive advantage over native plants and often grow so densely that they prevent angling and boating access to lakes and rivers. They also can restrict water flow causing floods, and when large amounts of plants die, the decay process takes oxygen from the water causing fish kills.

Many people are concerned about use of chemicals to control these plants, even though only approved chemicals are legally applied. Chemical control is expensive ($200 to $600 per acre per year). Mechanical control is another short-term solution but is about twice as costly as chemical control and can disrupt the fishery.

So what about these plant-eating fish?

The fish used to control aquatic plants in Florida are triploid grass carp. Grass carp, sometimes called white amur, come from eastern Asia. However, only triploid grass carp, which are artificially produced in hatcheries are allowed for stocking in Florida. This is because triploid grass carp are functionally sterile. If you stock too many and plants are eliminated in your pond, the problem will only last as long as the fish you stocked are alive--but that can be up to 15 years.

These fish can control certain aquatic plants in moderate- or small-sized lakes at a cost of about $20 to $250 per acre. In private ponds, golf course ponds, irrigation ditches and similar locations, where sport fishing is not the primary activity, stocking triploid grass carp can be an environmentally sound, cost-effective way of controlling aquatic plants. Stocking triploid grass carp in private ponds requires a permit from the Fish and Wildlife Conservation Commission (FWC), and it is illegal to possess any grass carp without a permit. The FWC's Aquatic Plant Section issues over 1,000 such permits each year.

Section personnel also monitor results of stocking triploid grass carp into 75 public water bodies, each larger than 10 acres, that total 62,700 acres. In these situations, where sport fisheries are important, the fish is not a panacea. If triploid grass carp eat too many plants, important habitat is destroyed, and sport fish populations can be adversely affected. Since the fish school together, they can severely impact plants in areas that are not heavily utilized by people and avoid congested areas where plant control is most important to boaters.

In conclusion, the FWC uses a permit program to allow citizens to purchase and stock triploid grass carp as a cost-effective means of controlling plants in private waters. The FWC also saves the state money by using the fish prudently in larger water bodies to reduce the need for expensive chemicals, but draws the line at stocking triploid grass carp in large open systems where the fish are unpredictable and could negatively impact the state's immensely valuable sport fisheries and the delicate balance of our natural ecosystems.