BBMP Fish Management Strategies: Action Items

III.        FISH MANAGEMENT STRATEGIES

Background:

A black bass population is governed by the rates of recruitment, growth, natural mortality, and fishing mortality, and thus black bass fisheries management generally involves actions that attempt to manipulate these rates. Length-based regulations coupled with daily bag limits are commonly used to manage black bass fisheries with the intent of reducing fishing mortality to increase the abundance of trophy-sized fish. Harvest regulations are set based on a pre-determined objective for the fishery. Angler expectations are a critical factor in determining the objective of a fishery, but expectations often vary between anglers, water bodies, and geographical regions. The guiding principal for the development of this BBMP is to work closely with stakeholders to provide a diversity of fishing opportunities. Therefore, we strive to make our management actions flexible to meet angler expectations, and to allow managers to adjust to changes in angler expectations and biological conditions.

Action items:

  • Establish customized harvest regulations to manage black bass populations at selected water bodies.

MeghannMeasuringBass.jpgTo optimize the effectiveness of harvest regulations to meet angler expectations, specific regulations need to be established for each species of black bass on specific water bodies based on the best biological and sociological data available. The ability to use lake or river specific regulations for individual species of black bass is critical to effectively manage fisheries, but moderating the number of regulations is important to prevent confusion or discouraging participation.

Harvest regulations have been used across the country in attempts to improve bass fishing (Wilde 1997; Allen et al. 2002; Carlson and Isermann 2010). However, the success of length limits to increase abundance and influence size structure of largemouth bass populations has been inconsistent. For example, Wilde (1997) concluded that minimum length limits generally improved angler catch rates but did not influence size structure, whereas protective slot limits had some ability to increase both variables. Length-based harvest regulations are typically initiated under the assumption that exploitation (measured as the percent of the population that is harvested) is negatively affecting abundance and size structure (Carlson and Isermann 2010), and thus the success of length limits to increase abundance and size depends on the fishing mortality rate, as well as the natural mortality rate, rate of recruitment, and growth (Wilde 1997; Allen et al. 2002). However, approximately 95 percent of state fish and wildlife agencies reported an increase in voluntary release of legal-sized largemouth bass in the mid-1990s (Quinn 1996). Myers et al. (2008) documented large increases in the voluntary release rate of legal-sized largemouth bass from the late 1970s to early 2000s. This temporal trend in largemouth bass voluntary release has resulted in declining mortality rates of largemouth bass since the mid 1970s, which lessens the response of fisheries to regulations and makes it more difficult to detect the effects of regulation changes (Allen et al. 2008). Nevertheless, even when overall mortality is relatively low, exploitation of the largest fish can be much higher (Henry 2003) indicating that size-selective mortality could still negatively affect largemouth bass fisheries, particularly when management goals include trophy fisheries (Allen et al. 2008). Voluntary release rates and exploitation rates of largemouth bass in small lakes (less than 1,000 acres) is an important consideration, since most studies evaluating this have been on large water bodies that receive a high percentage of fishing effort from tournament anglers.

Despite increased voluntary catch-and-release by anglers, exploitation can still be an important factor regulating size structure. There is evidence that more restrictive regulations such as high minimum length limits, large protective slots, and mandatory catch-and-release regulations may increase the number of trophy-sized fish (Hughes and Wood 1995; Wilson and Dicenzo 2002; Myers and Allen 2005; Carlson and Isermann 2010). Data on population dynamics (e.g., growth, recruitment, and mortality), habitat, and angler expectations should be considered for harvest regulations to maximize their effectiveness at reaching objectives. Additionally, for harvest regulation to be effective there must be adequate presence of law enforcement.

Some of the current black bass harvest regulations were not set for a specific objective based on biological and/or sociological data. Regulations have not always been evaluated to fully determine their effectiveness, particularly since it is difficult to separate changes in a fishery resulting from a regulation and changes due to environmental conditions (Buynak et al. 1991). Therefore, we must attempt to evaluate past regulations with existing data, and continue to collect population dynamics data on lakes and rivers to identify potential candidates for regulation changes through use of age-structured population modeling (e.g., stock assessment). Exploitation studies should be conducted on priority water bodies for all black bass species to determine if overall and/or size-specific exploitation is having population-level effects on small and large lakes. Any regulation changes should be evaluated for 10 years after implementation to determine success based on stated objectives (e.g., increased abundance, increased size structure, increased angler satisfaction or catch rates).


  • Determine the potential effects of bed fishing on black bass populations.

The BBMP public survey and the BBMP TAG both identified bed fishing as a concern. Schramm (1985) concluded that there were no differences in abundance of spawning adults and young-of-the-year largemouth bass in protected spawning areas and unprotected areas of Lake George, Florida; however, the experimental design and other confounding factors prevented definitive results. Model simulations have suggested that bed fishing in Florida does not likely have population-level effects (Gwinn and Allen 2010). However, fish could be more vulnerable during spawning than the model considered. There is a paucity of field studies on this topic in Florida and a comprehensive study to determine the effects of bed fishing on bass populations in Florida is needed. Human dimensions studies are also needed to determine what portion of anglers would support regulation of bed fishing either in general or in site-specific areas, should science tell us that protection of spawning fish would make a noticeable difference.


  • Ensure genetic diversity, fitness, and conservation of Florida largemouth bass.

WireCodedTagging.jpgFlorida largemouth bass are endemic to peninsular Florida and are the foundation of Florida's world famous trophy bass fishery. Agency studies revealed that some bass populations in south and central Florida were contaminated with northern largemouth bass alleles (i.e., genes) by historical stocking practices. Private fish producers continued to import northern largemouth bass and their hybrids into Florida and private citizens stocked them into ponds and lakes in the southern and central part of the state during the 2000s (Porak et al. 2007). Intergrade largemouth bass populations were found farther south than previously recognized (Barthel et al. 2010).

There are many management practices that will help conserve the genetic integrity of Florida largemouth bass. These include: 1) educate private hatcheries and the public about a new rule that made northern largemouth bass and their hybrids conditional species (requiring a permit) south and east of the Suwannee River and develop appropriate enforcement strategies, 2) test and certify brood fish at the Florida Bass Conservation Center (FBCC) to ensure that only pure Florida bass are stocked in their native range throughout peninsular Florida, 3) use high numbers of hatchery brood fish to guarantee genetic diversity of hatchery fish that are released into public waters, 4) use only wild-caught hatchery brood fish to avoid domesticated hatchery fish that would be less fit to survive in the wild after they are stocked, and 5) minimize out breeding among genetically divergent groups of populations by only stocking fish that had parents obtained within the same geographical area designated by FWC as a Genetic Management Unit (GMU).

Austin et al. (unpublished manuscript) determined the current raceway breeding practices at the FBCC maintain substantial portions of genetic diversity of the breeding stock and support continuation of current breeding protocol used at this hatchery. Establishment of four or five GMUs (Porak et al. 2007) is supported by black bass genetics research (Barthel et al. unpublished manuscript) and FWC's genetics policy for release of fish (Tringali et al. 2007). In the short term, continue research on hatchery brood fish genetics, genetic structure, and diversity of Florida bass populations, and genetic composition of bass that are privately produced and stocked into Florida ponds and lakes. In the long term, evaluate the potential for selective breeding of trophy bass or production of triploid or gynogenetic triploid bass for select trophy bass management lakes. Evaluate and if possible prevent further hybridization of shoal bass with other black bass species. Determine genetic makeup of Florida population of Suwannee bass to monitor and prevent, if possible, hybridization with other black bass species.

  • Ensure the genetic integrity, fitness, and conservation of endemic black bass within Florida panhandle river systems.

LMB-ZonesMore than half of the recognized black bass species (Micropterus) are present in Florida Panhandle streams, including the two species with the most restricted ranges, i.e., shoal bass (M. cataractae) and Suwannee bass (M. notius). Although habitat degradation is the most serious threat to panhandle bass populations, there is potential for interspecific hybridization to pose a more immediate threat in some cases. In other states, introductions of non-native species have led to introgressive hybridization and genetic swamping of populations of endemic species. Of all the black bass species, spotted bass appear to be the most opportunistic and hybridization has occurred between redeye X spotted bass (Barwick et al. 2006), largemouth X spotted bass (Godbout et al. 2009) and smallmouth X spotted bass (Pierce and Van Den Avyle 1997; Koppelman 1994). Recently in Florida, shoal bass X spotted bass hybrids were discovered in the Chipola River (Porak and Tringali 2009). The FWC has implemented a genetic study to help conserve native black bass species by (1) determining which species are present in panhandle streams and (2) monitoring populations for evidence of hybridization between species. Thus far, these investigations have uncovered two genetically distinct forms of spotted bass (M. punctulatus and M. sp. cf. punctulatus) in panhandle streams, one of which was previously unrecognized and has yet to be described (M. sp. cf. punctulatus). Members of this provisional taxon appear to be more closely related to Guadalupe bass (M. treculi) than northern spotted bass (M. punctulatus) and may be native inhabitants of western panhandle coastal lotic systems. Genetic studies have also documented that Chipola River shoal bass are hybridizing with M. sp. cf. punctulatus, M. punctulatus; and M. salmoides. During the course of three sampling years, nearly 10 percent of the presumptive shoal bass collected from the Chipola River were hybrids. To determine whether the genetic integrity of this important population of shoal bass is threatened by introgression, genetic samples must continue to be collected at regular intervals and additional work needs to be devoted to identifying factors that are responsible for hybridization. This includes gathering information on previously unrecognized forms of spotted bass, M. sp. cf. punctulatus.

  • Stock fingerling (Phase-I; about 1-inch long) largemouth bass into new reservoirs and into lakes following major fish kills or droughts.

HatcheryTruck.jpgLakes with good water quality and habitat do not need to be stocked with largemouth bass because recruitment is adequate to sustain the population. Lakes that have dried up and then reflooded or newly constructed reservoirs can benefit from a stocking of hatchery produced largemouth bass. Stocking fingerling largemouth bass should be successful during the first year after flooding due to tremendous production of small prey and low numbers of large predators. Restocking fingerling largemouth bass following a significant fish kill can expedite recovery of a fish population.

  • Stock advanced-sized (Phase-II, 4-6 inches) largemouth bass fingerlings into water bodies where recruitment is limited.

FingerlingStocking.jpgSupplemental stocking of advanced sizes of hatchery fish should be more successful than stocking fingerlings in certain situations, because larger hatchery bass should be able to eat a greater variety and size of prey (Loska 1982). From an ecological standpoint, larger sizes of hatchery fish should also have fewer predators that eat them (Wahl et al. 1995). Although some early attempts at stocking advanced sizes of hatchery largemouth bass in Florida lakes were not successful (Porak et al. 2002) new handling and nutrition protocols have been developed at Florida hatcheries. Larger sizes of hatchery largemouth bass (2.7-3.5 inch TL) fed on prey fishes and grew faster than their wild counterparts during their first year of life after being stocked in Lake Talquin, Florida (Mesing et al. 2008). Conversely, diet comparison of stocked advanced-size fingerlings and early-cohort age-0 wild largemouth bass at Lake Seminole, FL revealed that stocked fish had significantly higher rates of empty stomachs and wild fish had significantly more fish in their diet at seven days post-stocking (Pouder et al. 2010). Fingerlings stocked at Lake Talquin were raised on live prey in ponds, and fingerlings stocked at Lake Seminole were raised on pellets in artificial raceways, suggesting that rearing methods may play a critical role in supplemental stocking of advanced-size largemouth bass.

Further research is needed to determine hatchery protocols that could increase short-term foraging efficiency and survival. Research topics include 1) the potential benefits of conditioning hatchery fish to predators and prey prior to leaving the hatchery, and 2) evaluating the survival of pellet-reared vs. live-feed-reared hatchery largemouth bass. If it is determined that supplemental stocking of pellet-reared largemouth bass is not successful, alternative approaches should be considered for use of cultured bass in fisheries management (e.g., genetic stock enhancement - see genetics section).

  • Stock supplemental forage into small water bodies to improve growth rates of largemouth bass.

Ample forage must be available for bass to exhibit the fastest possible growth rates and highest possible population densities. For example, lake chubsuckers are a critical prey species for trophy-sized largemouth bass (Porak et al. 2002). Some water bodies may support a population of prey species that is not currently present, or augmentation of a prey species that is present at low densities. Examples of such cases include restoring the population of a prey species following habitat restoration projects or following cultural eutrophication that results in increased plankton production.

  • Manage impacts caused by exotic fish species on bass populations in Florida.

Past research in Florida has shown that non-natives generally increase overall carrying capacity as they fill underutilized niches without negatively impacting native black bass. However, introductions of new exotic species have the potential to affect bass populations negatively through foraging on bass, direct competition for food, competition for habitat, and habitat degradation. There is an important environmental and economic concern associated with the introduction and expansion of any unplanned exotic species. Flathead catfish have the potential to impact riverine species such as shoal bass and Suwannee bass. Although stocking triploid grass carp has proven cost-effective and environmentally sound in ponds, overstocking of grass carp has led to bass fishery declines through habitat degradation in some lakes. Armored catfish species continue to expand their range to the north throughout the state with largely unknown impacts. FWC will continue to educate the public about the importance of minimizing new introductions and further spread of existing non-native populations. Future research will be conducted to determine any potential negative impacts of exotic species.

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