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.
To
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.
Florida
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.
More 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.
Lakes 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.
Supplemental 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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