ARTICLE COURTESY OF: Florida fish and wildlife conservation commission.
Lake Okeechobee is Florida’s largest lake and the second largest body of fresh water in the contiguous United States. The word Okeechobee comes from the Seminole Indian language “Oki” (water) and “Chubi” (big) and means “big water.” These early Floridians chose the name well. Vast surface area (730 square miles), shallowness (averaging only nine feet deep) and enormous habitat diversity makes the ecosystem unique on the North American continent. The lake is a multiple-use resource, which supports valuable commercial and sport fisheries, provides flood control, and acts as a reservoir for potable and irrigation water for much of south Florida.
Lake Okeechobee is located on the south-central portion of the Florida peninsula at latitudes 27o 12’N to 26o 40’N and longitudes 81o 07’W to 80o 37’W. Major natural tributaries to the lake are Fisheating Creek, Taylor Creek and the Kissimmee River. Sheet outflow occurred historically across the entire southern rim into the Everglades. Prior to the 1900’s, water quality was characterized as clear and alkaline, and bottom sediments were described as “clean sand.” Levee and canal construction during the first half of the century confined the lake to a smaller area, eliminated overflow along the south shore, and facilitated back-pumping of excess water from the Everglades agricultural area into the lake. During the past 30 years, rising nutrient levels and periodic increases in the lake stage regulatory schedules have decreased habitat quality and pushed the system nearer a hyper-eutrophic and ecologically undesirable state.
Primary sources of lake water include rainfall (30%) and major tributaries, canals and runoff (70%). Evaporation accounts for 70% of water loss, with the remainder exiting through engineered outflows. High water levels are maintained from October through March (dry season), while low water levels are maintained from June through August. Shallow depth, long fetch and moderate winds combine to preclude thermal stratification. Regular mixing by wind and wave action ensures dissolved oxygen levels adequate for biological processes throughout the water column. Water temperatures average between 59o F (14o C) in January to 86o F (30o C) in August.
Lake Okeechobee is nationally recognized as supporting high quality largemouth bass and black crappie fisheries. The lake also supports a commercial fishery dominated by catfish species. However, the commercial fishery is also nationally unique in that a limited entry fishery (ten nets) exists for haul seine gear which is permitted to legally harvest and sell bluegill and redear sunfish. Freshwater fishing retail sales in the five counties surrounding Lake Okeechobee were estimated at more than $117 million during 2000. Biologically, Lake Okeechobee can successively support recreational and commercial fishery interests. Fishery management concerns on Lake Okeechobee not only require allocating available fishery resources between recreational and commercial interests, but must also be concerned with resolution of socio-political issues that result from user conflicts.
Aquatic plant communities benefit fish by providing spawning habitat, serving as refuge areas from the environment and predators, and support an intricate food web by providing nutrients for invertebrates and herbivorous fishes, which serve as forage. Despite ecological advantages provided by aquatic plants to fishes and wildlife on Lake Okeechobee, controversy over management of vegetation continues among federal and state agencies with regulatory authority for aquatic plant management, water quality and supply, flood control, and fish and wildlife management.
Changes in water level and differences in plant community structural complexity and water quality within vegetation communities exert the greatest effect on fish distribution in the littoral zone of Lake Okeechobee. Historically, bulrush has yielded the highest average numbers for total fish and game fish in block net sampling conducted on Lake Okeechobee. Importance of bulrush as habitat for adult game fishes has long been recognized by fisheries biologists, and bulrush is frequently planted during lake restoration and habitat enhancement projects.
Submersed vegetation types provide important habitat for forage fish, such as minnows shiners, and small bream. A positive relationship between hydrilla and production of juvenile game fish and forage fish has been documented by fisheries biologists. Dominant fish species abundance estimates for hydrilla, eelgrass, and Illinois pondweed (peppergrass) were similar, which indicates equivalent habitat value for these vegetation types.
The hurricanes on Lake Okeechobee during 2004 (particularly Hurricanes Frances and Jeanne) caused brief high water level surges to over 18 feet and, together with high winds, had a devastating effect on many plant communities. From the constant beating of high wind and waves, thousands of acres of plants such as bulrush, peppergrass, eelgrass and hydrilla were uprooted or broken off. Plants near the bottom or in protected areas were subjected to die-off from little or no sunlight reaching them as a result of highly turbid water over a long period of time.
