BBMP Fisheries Tools

FISHERIES MANAGEMENT TOOLS

Monitoring and Data Gathering:

Fisheries biologists use a variety of sampling tools for studying bass populations. Electrofishing is a nonlethal sampling method that passes controlled electric current through the water to temporarily immobilize fish. The effective depth-range of the electric field is about 6 feet deep, limiting electrofishing to shorelines and other shallower areas. Stunned fish are collected with dipnets for a variety of studies, including documenting their length and weight, for overall health diagnostics and to check for tags. Electrofishing is one of the most efficient methods for quickly collecting fish or assessing a water body's fish populations.

Nets may be better than electrofishing for certain needs. Biologists may use a seine for quantitative estimates of young bass or forage along a shoreline. Blocknets are larger nets, varying from 0.1 to 1.0 acres in size. Along with a fish poison, rotenone, they may be used for documenting the most accurate quantitative estimates of bass and the total fish assemblage.

Angler interviews (creel surveys) provide important information not available from other sampling, both about a fish population and about the anglers themselves. For instance, scientists can estimate angler catch rates for certain species that are used as an index of abundance; which species in a given lake are most targeted; how much angler pressure or effort is focused on a resource; how many fish are being removed from a system by harvest; and angler satisfaction.

Using these various sampling methods, fisheries biologists can obtain important information regarding fish populations. For example, marking (using various tags or fin clips) and releasing bass can provide an estimate of a lake's total bass population, based on the number of marked fish caught on subsequent electrofishing runs. Similarly, blocknets of a known area (such as a quarter acre) can be helpful in estimating fish densities - for instance the number of bass per acre in a given canal or lake. Looking more closely at individual fish, an index comparing the weight of a fish with its length will reveal whether fish in a particular lake are well-nourished or underfed. Using fish-length information, biologists can produce a length-frequency graph that shows the number of fish of various sizes in a given population. Biologists can tell the age of a bass from a set of "ear bones" in the fish. Marks, similar to tree rings are laid down each year. From samples of ages and sizes of fish, one can determine whether the "year-class" is strong or weak, and how well the fish has grown. Taking into account age data from the same fish can reveal clues about the fish population's rate of reproduction, growth, and mortality - all important factors for fisheries management. Biologists also tag fish with radio or acoustic tags. They can then track the fish with electronic receivers and determine more about their habits. Currently, biologists are using this technique to identify shoal bass spawning areas on the Chipola River, so they know which areas are important to protect.

Habitat Management:

A primary tool of habitat management, where fish are concerned, is aquatic vegetation management. Aquatic plant management includes the encouragement of plant growth, which is usually accomplished by improving water clarity, or by fluctuating water levels. Additionally, biologists have been successful planting species such as eelgrass and bulrush.

The most common type of aquatic plant management for nuisance plant species (usually exotics from other countries such as water hyacinth and water lettuce) is spraying with approved herbicides. Lack of desirable native vegetation, often coupled with high nutrient levels that stimulate exotic plant growth, is probably the most common problem in Florida lakes.

Other tools for habitat improvement include muck removal, fish attractors, water quality management, and aeration systems. Drawdowns, complete dewatering of small lakes, or water level manipulations can also be very effective in rejuvenating older lakes by allowing oxidation and decomposition of muck on the exposed lake bottom, and stimulating rapid aquatic plant growth when water levels are raised back up. Drawdowns can also be utilized to control excessive vegetation in north Florida lakes, where plants can be exposed to freezing temperatures during winter. A part of this practice may even include temporarily raising the water a few feet and then rapidly dropping it to strand floating plants. Similarly, important Florida waters such as the Everglades and Lake Okeechobee are healthiest - along with their fish populations - when subjected to periodic water level fluctuations and dry periods that mimic naturally occurring water level fluctuations.

Fish Management:

In a large natural setting, dealing with an individual fish's health is impossible, so population management is the focus. Fish management should be thought of as any action taken to achieve a pre-determined outcome with regard to the fish population or fishery. Regulations and stocking are important tools that take into account concern for species diversity, predator:prey ratios, and fish genetics. Scientifically sound rules, backed by law enforcement expertise and personnel to implement them, allow FWC to manage Florida's freshwater fisheries for "optimum sustainable use." Optimum means that harvest and gear regulations are adjusted to local conditions to a practical degree (without becoming too complex) and to concur with local anglers and angling business preferences. Such rules must, however, ensure long-term sustainability of a quality fisheries resource by preventing overfishing. Also note that by referring to sustainable "use," we reflect the value of catch-and-release and/or harvest. The multiple recreational use concept also must be considered in management decisions. For example, besides bass anglers, we need to consider bream, crappie and catfish anglers, duck hunters and paddlers. However, fish populations are dynamic, and as they change, primarily due to the ecosystem's ability to produce new "recruits" (see recruitment in glossary) and the effects of angling pressure, regulations to protect them also need to adjust. In addition, fish kills, habitat alterations, droughts or hurricanes can cause dramatic changes in a fishery, requiring adaptive management.

Stocking fish is another important fisheries management tool. Many anglers see this as a cure-all; however, if habitat and the food base are not adequate to ensure natural recruitment, and there is an abundance of natural predators, stocking even large numbers of small bass (Phase-I) may do little good. Efforts to grow larger (Phase-II) bass and to learn to stock them at appropriate times and locations to take advantage of abundant natural prey (e.g., after shad spawn) are being evaluated and refined. Stocking a mix of sport fish and forage fish to create a balanced fish population works well in new or renovated lakes that do not yet have established predators. Therefore, biologists usually use other tools, such as habitat manipulation and regulations, to manage lakes with established bass populations. An abundant bass population in a lake can also crop small sunfish, so remaining sunfish have adequate forage to grow quickly and to larger sizes. Manipulation of fish genetics also plays a role; a good example is protection of the Florida largemouth bass gene pool, because the Florida bass are better adapted to our subtropical environments and grow larger than the northern subspecies.

People Management:

People management encompasses education, outreach, information distribution and marketing efforts. Educational activities, such as fish camps that teach conservation stewardship along with fishing skills and safety, can have a long-term impact on participants' appreciation for nature and enjoyment of a lifetime of fishing and outdoor recreation. Outreach events provide opportunities for a large number of people to learn about FWC activities and the importance of conservation management, and perhaps to experience fishing for the first time. Communicating a wide variety of information about current regulations, fishing sites and forecasts, useful fishing tips, handling methods for effective catch-and-release (including photographing your catch), alternatives to skin mounts and live weigh-in tournaments are all important management activities. FWC uses printed materials, the Internet, social media (e.g., Facebook, Twitter, YouTube, and Flickr), television and radio shows, as well as its presence at various events where anglers congregate, to provide face-to-face dialogues about bass fishing. "People Management" also includes marketing activities such as our five-year fishing license promotion, advertising the "Go Fishing" largemouth bass tag, designating a Free-Fishing Weekend in April, and working with local communities and businesses to explain the social and economic value of recreational fishing and the need for access and fishing facilities.