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Biologists monitor long-term trends of Florida’s freshwater resources.

  • The Freshwater Fisheries Long-Term Monitoring program began in 2006.
  • Each year data is collected on the fish community, habitat, and sport fisheries of over 50 waterbodies.
  • Fish are collected using electrofishing and trawls with notable health conditions documented.
  • Aquatic plant surveys are conducted during summer months and the data are used to monitor changes in lake vegetation.

The Fish and Wildlife Research Institute (FWRI) Freshwater Fisheries Research section began the Long-Term Monitoring Program for Florida’s freshwater resources in 2006. What started as a focus on fish data for lakes has expanded to include river systems and aquatic habitat. Researchers’ primary objective is to track freshwater fisheries and habitat trends over time using standardized methods that help ensure the integrity of the data collected across the state. This information can then be used to assess the overall health of Florida freshwater resources, direct research efforts, and make management decisions.

Each year, biologists collect data on the fish community and sport fisheries of more than 50 lakes and rivers statewide. They add this information to a large database where it is available for use in future studies or evaluations conducted by researchers and fisheries managers. As of 2019, the database contained over 3 million records, and the number will continue to grow as the project continues.

Data Collection Methods

Biologists with FWRI, as well as other FWC divisions, use a variety of methods to sample freshwater fish communities. The type of equipment used depends on the target species, sampling location, and habitat. Researchers most commonly use two types of equipment to collect fish data in Florida’s lakes and rivers:

  • Electrofishing is used to collect fish in shallow water, 2-6 feet deep. The most common species are largemouth bass (Micropterus salmoides) and bluegill sunfish (Lepomis macrochirus), which have been collected in every lake sampled. This gear is also used to assess sport fish populations in the spring.
  • Trawling is used to collect fish in open water during the fall. The trawl boat pulls a net suspended near the lake bottom as it moves forward. The net dimensions are configured to target young black crappie (Pomoxis nigromaculatus), and using this gear helps fisheries biologists assess populations of this popular sportfish.

In addition to length and weight measurements, fish collected during sampling events are also observed for abnormalities. Any notable health conditions, such as sores or lesions are recorded in order to monitor fish health trends.

Since the beginning of the Long-term Monitoring Program, water quality and details about the amount and types of plants present have been recorded with each fish sample.

However, in 2015, a formal aquatic vegetation monitoring program was put in place. During summer months, boats equipped with sonar mapping devices criss-cross each lake along evenly spaced transect lines. Biologists also collect plant samples at points along the transect lines using a plant rake. This information allows biologists to produce detailed plant maps for approximately 50 lakes each year.

Importance of Monitoring Data

Using the above methods, biologists monitor and measure the following fish metrics:

  • Species diversity – an index of the number of species and abundance of each that make up a fish community
  • Species richness – a component of species diversity that represents the number of different fish species present in the community
  • Catch rate – an index used to estimate the relative abundance or density of fish, and can include values for all fish (total catch rate) or groups of fishes (e.g., catch rates of sport fishes or nonnative fishes)

The long-term monitoring project is another opportunity for scientists to monitor freshwater fish communities that are valuable resources to the state of Florida. State, federal and academic personnel use the data collected to develop management strategies and conduct related research as scientists produce a more complete picture of long-term trends. Additional information like water quality and plant data are used to help explain changes observed in the fish community or fishery.