Biologists explain the science behind black crappie length limits and answer common questions from anglers.
Biologists measure black crappie during a routine sampling trip.
Biologists with the FWC's Fish and Wildlife Research Institute (FWRI) and Division of Freshwater Fisheries Management (DFFM) are often stopped by curious anglers who ask questions about their activities on the lake and the local fishery. As fall approaches, many of Florida’s seasonal residents will be joining the locals in the hunt for black crappie. During this time, most of the crappie questions biologists receive pertain to local harvest regulations. Crappie length and bag limits vary greatly across much of the United States. With anglers from different parts of the country fishing Florida waters during crappie season, confusion can occur. The following frequently asked questions and responses explain the science behind Florida’s crappie regulations.
Why doesn’t Florida have the same crappie length limits as other states?
Crappie length limits vary to reflect the differences in crappie populations from region to region. Florida lakes are in many ways different from lakes and reservoirs in the Midwest, and these environmental factors affect the way black crappie live and grow. Florida’s warmer climate leads to a longer growing season and crappie here have different food sources, predators and spawning seasons. As a result, the crappie population in a warm Central Florida lake is often much different from a population in a cold, deep reservoir in Ohio. Because of this, size limits and other regulations must be tailored to each crappie population.
What do crappie regulations accomplish?
Different water bodies can be managed to accomplish different goals. For example, the size limit at Lake Jackson in Osceola County is designed to produce very large (trophy) crappie. A different size limit at Lake County’s Lake Griffin, on the other hand, was implemented to increase the total weight anglers harvest by increasing the size of the fish they take home. Other regulations, such as the statewide bag limit, are simply designed to help sustain the crappie fishery.
How do length limits work?
When an angler releases a fish in accordance with current regulations, several things happen. By putting fish back anglers keep the total number of fish in the lake up. It also gives released fish more time to grow and a chance to reproduce.
|Biologists collect and measure crappie to determine proportion of fish in each size
class in the lake’s crappie population.
Why don’t length limits
work the same on all lakes?
Studies in several states have revealed length limits succeed in producing bigger fish or higher total catch by weight if:
- fish growth is fast;
- natural mortality (the proportion of fish dying of natural causes) is low; and
- fishing pressure (percent of fish being harvested) is high.
If growth is slow, fish may not grow to legal size. If a high number of fish die from natural causes, the fish anglers release may not have a good chance at reaching regulation size. If fishing pressure is low, anglers may harvest so few fish that a regulation would result in very few additional fish being released, making the regulation ineffective. On the other hand, if growth is fast, natural mortality is low and fishing pressure is high, a size limit could produce more big fish by allowing the smaller ones the chance to grow, reproduce and be caught again another year.
How does the FWC determine how to set regulations?
The FWC makes science-based decisions when determining how to manage Florida’s natural resources, including black crappie. The process of determining and implementing a crappie length limit for a Florida lake involves several steps:
- Set a goal for the fishery, with input from local anglers.
- Collect adequate data to evaluate whether or not the regulation will accomplish the goal.
- Hold public hearings to get more feedback from stakeholders.
- Present the proposed regulation, data and public comments to the FWC Commissioners at a quarterly Commission meeting where the public is again invited to provide input.
- Commissioners make a decision on whether or not to implement the regulation.
- Biologists continue to monitor the lake to assess how the regulation affects the fishery.
If I think a regulation might benefit the lake I fish, what should I do?
Biologists often begin the process of investigating a potential regulation when local anglers express concern about a fishery. It then takes a considerable amount of effort, time and resources to collect the necessary data to evaluate whether a regulation might improve the fishery. FWC biologists are open to talking with any anglers who think that their local lake would benefit from a specific regulation.
What kinds of data do biologists collect?
When a length limit is proposed, biologists need to find out three things: growth rates, mortality (death rates) and angler effort and harvest.
|Anglers fill coolers with the carcasses of
their filleted catch. Only those with head
and tail still attached are used for research.
To estimate growth rates, biologists must know how big fish are at any given age. One way they obtain this information is from carcasses of angler-harvested crappie. Biologists collect these carcasses at cleaning stations near local fish camps or boat ramps and then measure and age each fish. By doing this, biologists can learn how fast fish grow, at what age they reach the proposed minimum size limit and what size fish anglers tend to keep.
Mortality (Death Rates)
Biologists can also use the carcasses to estimate mortality rates by analyzing the proportion of fish in each age group in the harvest. To separate natural deaths from angler harvests, biologists collect live fish and mark them with reward tags. The tags have a phone number on them so anglers can report catching tagged crappie to biologists, who can then gather information such as whether or not the fish was harvested. This helps biologists estimate the proportion of the population lost to harvest.
Angler Effort and Harvest
Biologists assess fishing effort and harvest using creel (angler) surveys. In these surveys, biologists count the anglers on the lake and politely approach boats to find out start time, targeted species, number of fish caught and number of fish harvested. With this information, biologists can estimate how many people fish the lake in a season, what they are fishing for, how many hours they fish for each species and how many fish are caught, released and harvested. When a regulation is being considered for a lake, biologists may also ask anglers their opinion of the regulation to find out if there is support among those most affected by it.
After everything has been collected, biologists put the data into models to estimate how the fishery might change under different regulations. Once a regulation takes effect, biologists continue to monitor the population and conduct creel surveys to gauge angler satisfaction and record the number and size of fish that are being harvested.
These data are collected in cooperation with the local anglers and FWC biologists could not complete this work without them. Browse by region to find more information on Florida’s local harvest regulations.