In Florida, more people spend more time fishing (three times more) than they do visiting Walt Disney World. Florida is the number-one state visited by anglers (three million each year) and surpasses all other states in fishing retail sales, jobs and salaries, with an overall economic output of $7 billion (2002). Of this, freshwater fishing generates nearly $1.8 billion annually.

Besides catching fish, resident and tourist snorklers and divers also enjoy delightful hours of fish-watching. In addition to providing pleasurable experiences for people, Florida's fisheries offer food to a wide variety of aquatic and terrestrial wildlife. Fish communities contribute to the health of aquatic ecosystems and are an integral component of maintaining a biological balance underwater.

Starting early	Stump knocking	Worth the trip!

Competing for a bass boat	Starting early	dinner

Submersed aquatic plants also generate oxygen, which helps keep the oxygen content high enough for fish and other submersed life. But like most environmental truisms, it's not all that simple. Overabundant submersed aquatic plant growth can consume oxygen and suffocate fish. One of the worst recorded fish kills in Florida public waters occurred in hyrdilla-covered Rodman Reservoir in 1985. Several cloudy days combined with a water column full of hydrilla consumed most of the oxygen in this 10,000 acre reservoir resulting in the death of more than 8 million fish.

Learn more about the ups and downs of the plant photosynthesis/respiration oxygen cycle.

It's true that effects of some invasive aquatic plants are beneficial to fish in some ways especially early in the infestation. As do native plants, non-native invasive plants provide surface area for algae and small animals to attach to and live on: this is fish food. As do native plants, non-native invasive plant infestations provide room for baby fish to hide from predators.

And as do native floating plants, non-native floating invasive plants provide the "edge effect", a place where fish are more likely to be caught. And vast stands of hydrilla or mats of water hyacinth concentrate fish into a smaller area of open water, especially along the edges, causing the "reef effect" which attracts fish and increases the likelyhood of catching them.

Fishing With and Without Plants We've heard, "I catch fish when there's hydrilla." We have no doubt of it. Invasive non-native hydrilla performs the fish-friendly functions of aquatic plants, just as do our native aquatic plants. As explained on this web page, there are more (smaller) fish in a hydrilla infestation and there is the edge effect as well as the reef effect. In some ways, these hydrilla attributes make it easier to catch fish; naturally the fisherman who's catching fish thinks highly of the place he's catching fish. All other things being equal (clean water, adequate oxygen, native plants), it is just as possible to catch fish where there is no hydrilla. It just requires that you be more of a traditional fisherman - one who scouts the lake for and exploits fish-concentrating obstructions, lake holes and native plant edges... In a fishing lake of native plants and open water, traditional skill and patience will reward you with the thrill of catching larger fish!

However, fisheries research and closer analysis also reveals that invasive plant infestations beyond a certain extent actually stunt the growth of fish. Research shows that sometimes there may be more fish in a hydrilla infestation, but they'll be smaller fish.

Also, invasive plant infestations make it difficult to catch fish: try dragging a lure through hydrilla; try tossing a hook into a 10-50 acre mat of water hyacinth.

The bottom line is, native plants are just as able to provide the same beneficial functions as do the invaders, and native plants have provided these benefits for eons before the invaders came.

For example, eel grass, pondweeds, bladderwort, the submersed sagittarias and others are some native plants that provide underwater plant surface area for fish food (those periphyton and small animals that attach to plant parts).

Native plants also oxygenate the water. And native plants are eaten by birds and fish, just as hydrilla is. Native plants on the other hand seldom fill the water column or form masses at the water surface, restricting navigation and recreation, consuming oxygen or creating flood control problems.

Under certain conditions, fish kills could occur from oxygen depletion after plant death caused by herbicides. The dead plants are attacked by bacteria that cause the plants to decay. The increased bacteria use up oxygen in the water. When the oxygen in the water gets too low, fish may suffocate if they cannot escape to more oxygen-rich waters.

These days, when particular circumstances arise, such as the use of specific herbicides on cloudy days, plant managers take dissolved oxygen readings in order to be sure there is enough oxygen in the water to support fish life while plants decay.

Learn more about fish kills here.

Fish stocking
To build up fish populations in Florida, the Florida Fish and Wildlife Conservation Commission stocks between 3 and 4 million fish annually, in more than 100 lakes and rivers that are accessible to the public.

Fishing licenses
In most cases fishing licenses are required in order to fish in Florida's waters. However there are numerous exemptions for children, retirees, cane pole anglers, and military personnel. Fishing licenses can be purchased at most tackle shops, marinas, and retail stores that sell fishing equipment.

Fishing Licenses in 2004 * Residential Florida freshwater fishing licenses cost $13.50. * Resident freshwater/saltwater combination licenses are $25.50. * Non-resident seven-day freshwater licenses are $16.50. * Non-resident one-year freshwater licenses are $31.50. To purchase an instant license for $13.95 plus a convenience fee, call 1-888-347-4356.

To support fish populations and promote the angling economy in Florida, the U.S. Fish and Wildlife Service annually sends $8.1 million toward game fish restoration. Private industries such as fish camps, fishing tournaments, and nature theme parks also support fish populations in Florida.

Anadromous Fish
Anadromous fish are those that migrate between saltwater and freshwater, and may be found in Florida's rivers, springs, and connected lakes. Anadromous fish are an essential part of the freshwater ecosystem as these migratory animals collect nutrients from the ocean as they grow and transport the nutrients (that is, in their bodies) upstream into freshwater habitats.

Each year the U.S. Fish and Wildlife Service stocks more than 1.5 million anadromous fish into Florida's freshwater ways. Such fish include:

mullet	sturgeon

sheepshead tarpon snook

Once a non-native fish becomes established in Florida's aquatic ecosystem, it competes with native species and disrupts the natural balance. Non-native fish that successfully survive after release in Florida's waterways are generally more aggressive and may out-compete native fish for food or habitat. Once non-native fish have become established, fisheries experts are hard-pressed to find means of eradicating the aquatic invaders.

pleco

However, unusual cold spells and occasional freezing temperatures can help reduce invasive populations. For example, millions of tropical South American pleco, an invasive fish species introduced by the aquarium industry, were eliminated when below-freezing weather hit Lake Kissimmee in 2001-2002.

View more pictures of Florida's freshwater exotic fishes on the Fish & Wildlife Conservation Commission site. There is also the FWC Exotic Fish Identification chart (PDF download file).

Chinese grass carp

Excess growth of aquatic weeds causes great problems for Florida’s watersheds, as discussed elsewhere on this web site. The use of non-native herbivorous fish, such as the grass carp (Ctenopharyngodon idella Val.), is an important means of biologically controlling aquatic weeds, especially in private ponds and agricultural ditches. Learn much more about Chinese grass carp on this page of our web site.

Triploid grass carp, that purportedly cannot reproduce, are the kind of grass carp that are legally used in Florida. (The term "triploid" refers to having an extra set of chromosomes, which make the grass carp sterile). Using triploid grass carp makes it less likely that this non-native fish will itself become an invasive species: unwanted reproduction of grass carp could damage the habitats they were intended to repair.

A more recently recognized serious pollutant is mercury. Public advisories warning about fish consumption are issued by the state and local Departments of Health. Concern about mercury contamination in fish is growing in Florida because some fish have been found to contain methyl mercury above 1.5 parts per million, which is considered unsafe for human consumption. FWCC has compiled a list of Florida lakes where the fish are considered either safe for unlimited use, safe for occasional consumption, or unsafe to be eaten.

To check your favorite lake's status on mercury, go to this FWCC web page. The "unsafe mercury list" in Florida includes the Water Conservation Areas 2a and 3, and the Everglades National Park's Shark River Drainage, northwest of State Road 27. Both areas are in south Florida.

FEWER FISH
Drops in fish populations, such as in natural "fish kills" and longterm fish reductions, can occur for a variety of reasons including:

stabalized water levels and a muck buildup resulting from the accumulation of organic material on the floor of the waterbody, may reduce water oxygen levels and water depth as well as create unsuitable spawning conditions, thus selecting for certain fish species over others. Most Florida lakes are now connected to one another for flood prevention. People have moved into the watersheds so lakes are no longer allowed to flood and wash organic debris out of the lake basin or thin native plant communities. Businesses and agriculture rely on water so few lakes can or are allowed to dry and burn as in the past. The result of this stabilization is dense growths of invasive and even native plants and the corresponding muck buildup.

invasive plant infestations, resulting from a lack of invasive plant management, limits the full growth of fish, and limits spawning sites of certain fish such as bass; invasive plant cover can seal off the water/air interface and thus contribute to lowered dissolved oxygen

low dissolved oxygen that occurs when bacteria aid in the decomposition of plants and other organic matter, such as leaves and sediments that are flushed from adjacent swamps and marshes into lakes and rivers, creating depleted dissolved oxygen levels in the water, suffocating fish and other organisms; low "DO" also may occur when invasive plants like water hyacinths form mats at the surface, sealing off the water/air interface

lack of food for young fish (fry) which occurs when too many plants are eradicated from a waterbody, and the microscopic animals that small fish depend on for food live on those plants and are removed as well

low water levels that create crowded conditions and competition for space, food, and shelter; shrunken waterbodies crowd the fish populations, making it easier for anglers and predators such as alligators and wading birds to more easily harvest more fish

poaching fish that are protected or out of season or taking too many fish and exceeding catch limits can have devastating effects on fish reproduction and populations

Learn more about fish kills and oxygen depletion on our other web pages.

To find the lab or office nearest you, go to this FWCC web page.

The FWCC has also established 24-hour "Wildlife Alert" hotlines to investigate violations of Florida's wildlife laws. Information leading to an arrest can result in up to a $1000 reward. Numbers to call are: