Populations Of Largemouth Bass Micropterus Salmoides Research Articles

Variation in Reproductive Investment among Ohio Reservoir Largemouth Bass Populations

AbstractReproductive investment, expressed in terms of fecundity and egg quality produced by individual female fish, varies among populations for many species, reflecting plasticity in life history strategies related to intraspecific density dependence or environmental variability. Fisheries scientists and managers have long sought to understand differences in Largemouth Bass Micropterus salmoides population dynamics, yet basic life history traits, such as variation in reproductive investment, remain largely unknown. We determined the fecundity–weight and ovary energy density–weight relationships (where fecundity indexes egg quantity and ovary energy density indexes egg quality) for Largemouth Bass populations from 19 Ohio reservoirs and examined factors that were correlated with population‐specific differences. We found that both relationships varied among reservoir populations, with some interannual variation in reservoirs sampled in multiple years. We then related fecundity and ovary energy density to (1) population characteristics, including population density (as indexed by standard shoreline boat electrofishing CPUE, fish/h) and growth (as indexed by the growth coefficient k from the von Bertalanffy growth function); and (2) reservoir characteristics, including reservoir size (as surface area) and productivity (as Secchi transparency depth). We found that populations with greater fecundity also exhibited greater ovary energy density, indicating that the quantity and quality of reproductive output were greater in some populations than in others. Populations with high reproductive investment were associated with low Largemouth Bass density, fast growth, large reservoir size, and high productivity (i.e., low Secchi transparency). The among‐population variation in reproductive investment provides evidence of density‐dependent control of fecundity and egg quality.

Using Electrofishing Catch Rates to Estimate the Density of Largemouth Bass

AbstractCatch rates are commonly used to indirectly index population density, e.g., nighttime electrofishing to survey Largemouth Bass Micropterus salmoides populations. However, the relationship between catch rate and population density must be known in order for catch rate to serve as an accurate index. We sought to determine if Largemouth Bass electrofishing catch rate was linearly or nonlinearly correlated to population density in high density populations using measurement‐error models and Monte Carlo simulations. Previous studies of the relationship between Largemouth Bass electrofishing catch rate and density have occurred in low‐density populations (<50/ha). We hypothesized that high‐density Largemouth Bass populations may result in gear saturation during electrofishing sampling, i.e., too many fish for dipnetters to capture resulting in missed captures. This would therefore underrepresent the population's density. The nighttime electrofishing catch rate of 66–294 Largemouth Bass/h was linearly related to their population density (77–152/ha) over 15 experimental events. The linear relationship suggests electrofishing catch rate is an appropriate index of population density in similar high‐density Largemouth Bass populations.Received August 11, 2014; accepted December 3, 2014

Population characteristics of historically unexploited largemouth bass in southern New England water supply reservoirs

Recreational fishing can alter the demography and life history characteristics of fish populations. Unexploited populations are useful references for fisheries managers to place into context the extent of changes in exploited populations and the outcomes of management actions. Our objective is to characterize the largemouth bass Micropterus salmoides populations in two unexploited reservoirs in Connecticut and compare them with an exploited reservoir. Unexploited Hemlock Reservoir was characterized by large proportions of large fish in good condition with relatively low population mortality rates. Unexploited Easton Reservoir's bass proportional size distributions were more similar to exploited Mansfield Hollow Reservoir bass population. However, both unexploited reservoirs had higher catch per effort of stock-size and greater fish than Mansfield Hollow Reservoir indicating greater overall density of large fish. The study of long-term unexploited populations may become more important in the future as managers consider the evolutionary consequences of recreational exploitation.

Will the Expansion of Northern Snakehead Negatively Affect the Fishery for Largemouth Bass in the Potomac River (Chesapeake Bay)?

AbstractA modeling study was conducted to determine if the expansion of invasive northern snakehead Channa argus could negatively affect the largemouth bass Micropterus salmoides population size in Potomac River (Chesapeake Bay). Current distributions for both species were generated using catch records. Northern snakehead was not widely distributed during the study period and occurred mainly in upstream areas of tributaries. Many of these areas were moderately or highly suitable habitats for largemouth bass. Of sites where juvenile largemouth bass were collected, 10.6% were associated with northern snakehead. Using population modeling and measured predator–prey interactions, we determined that this level of co‐occurrence would result in a 3.8% reduction in largemouth bass population size. This prediction is consistent with current observations that indicate there has not been a negative trend in the largemouth bass fishery. As co‐occurrence was increased in the model, however, the negative impact of northern snakehead on largemouth bass monotonically increased. The time required for such increases in northern snakehead distribution is not known. If northern snakehead continues to expand its range in the absence of control measures, then our population model, with its assumptions, predicts a 35.5% reduction in the abundance of largemouth bass in the Potomac River.Received February 6, 2012; accepted June 7, 2012

Genetic Analysis Reveals Dispersal of Florida Bass Haplotypes from Reservoirs to Rivers in Central Texas

AbstractWe analyzed the genetic structure of putative largemouth bass Micropterus salmoides populations in nonstocked, wadeable streams of central Texas. Mitochondrial D‐loop sequences were generated for 69 fish sampled for this project. In addition, 27 largemouth bass and Florida bass M. floridanus specimens provided by the Texas Parks and Wildlife Department (TPWD) were sequenced. The TPWD samples represented stock lineages as well as wild fish from outside of the sampling region. Our analyses revealed the presence of both largemouth bass and Florida bass mitochondrial haplotypes at all sampling locations. Haplotypes of the nonnative Florida bass accounted for 26% of all haplotypes. The presence of Florida bass haplotypes at the sampling locations indicates that the influence of stocking reaches far beyond managed reservoirs. The admixture of nonnative genetic material can increase genetic diversity of native populations, but outbreeding depression, competition, and other negative impacts are of concern. Although the stocking of nonnative Florida bass in reservoirs may enhance fishing opportunities, it also has the ability to alter stream systems that are directly connected to stocked reservoirs.

Estimating Genetic Composition in Introgressed Largemouth Bass Populations: Does Age Matter?

AbstractIn estimating population‐level introgression for largemouth bass Micropterus salmoides populations, it is unclear which age‐class, if any, is most appropriate to sample and what biases may be introduced by the sampling of specific age‐classes. Estimates of introgression between Florida largemouth bass M. salmoides floridanus and northern largemouth bass M. salmoides salmoides in six populations were made based on seven microsatellite loci from different age‐classes and combinations of age‐classes. Levels of introgression were not significantly different for 40 of 42 pairwise age‐class comparisons within reservoirs or for five of six comparisons between age‐0 fish and adults. In addition, measures of precision based on each estimate were similar within reservoirs. These results suggest that age‐0 largemouth bass samples can be used to make accurate and precise estimates of introgression at the population level. However, these results also suggest that alternate year‐classes or combinations of year‐classes with or without the inclusion of age‐0 samples are equally suitable for estimating introgression at the population level. Thus, the selection of specific age‐classes to be sampled for estimating introgression in largemouth bass populations should be based on the efficiency with which the age‐classes can be collected.Received February 15, 2010; accepted November 17, 2010

Management of Largemouth Bass at Kentucky and Barkley Lakes, Kentucky

Largemouth bass Micropterus salmoides populations declined in Kentucky and Barkley lakes following a severe drought during Dec 1984–Oct 1988 and below normal rainfall in three of four years during 1989–1992. Regression models developed for both reservoirs indicated that recruitment of largemouth bass to age 1 was positively related to the electrofishing catch per unit effort (CPUE) of large age-0 bass and negatively related to annual rainfall amounts and the CPUE of all sizes of age-0 largemouth bass. These variables explained 73% of the variation in CPUE of age-1 bass at Barkley Lake and 60% at Kentucky Lake. We also developed regression models to estimate the recruitment of largemouth bass to the fishery at age 5 and older. Recruitment to the fishery at Kentucky Lake was positively related to the CPUE of age-1 bass and negatively related to reservoir discharge. This model explained 52% of the variation in recruitment to age 5 and older largemouth bass. Recruitment to age 5 and older fish at Barkley Lake was positively related to the CPUE of age-1 bass and rainfall and negatively related to reservoir discharge. The model developed at Barkley Lake explained 82% of the variation in recruitment of largemouth bass to the fishery. The models predicted that the largemouth bass fisheries at both reservoirs would decline through 2001 under the current angling regulations, which include a 356-mm minimum length limit and one fish less than 356-mm total length allowed in the angler's creel. We used these models, in consultation with the public, to change length limits to a 381-mm minimum length limit in an attempt to moderate the expected declines in older fish.

Mitochondrial DNA cytochrome b gene variation reveals different largemouth bass genealogies

A mitochondrial DNA character set based on cytochrome b gene variations is described that may be used in conjunction with established nuclear gene differences to assess largemouth bass Micropterus salmoides population structure and dynamics. Alignment of known cytochrome b sequences revealed two regions where the functional constraints of the molecule appear to be sufficiently reduced to allow several amino acid substitutions. Restriction analysis was used to probe nucleotide variation within one of these evolutionary hotspots, resulting in the discovery of fixed largemouth bass subspecific cytochrome b haplotypes. Application of two molecular character sets, one founded on fixed allelic variation in nuclear genes and the other on mtDNA cytochrome b diversity, revealed that in several Texas populations, where the Florida subspecies was introduced into extant populations of northern largemouth bass, hybridization was evident. The direction of the introgression vector could be determined through the combination of both character Sets.

Electrofishing Catch Rates as an Index of Largemouth Bass Population Density in Two Large Reservoirs

A shoreline electrofishing scheme with a stratified random design was developed for estimating largemouth bass Micropterus salmoides population density in Lake Norman, North Carolina, and Lake Wylie, North Carolina–South Carolina. Catch rates (number/100 m shoreline electrofished) of largemouth bass (≥200 mm total length) were linearly related (r = 0.98; P < 0.01) to population density estimates (number/hectare) obtained with mark-and-recapture methods.

Vital Statistics of a Largemouth Bass Population in Minnesota from Electrofishing and Angler-Supplied Data

Abstract Three methods of determining the structure of a largemouth bass Micropterus salmoides population were evaluated. Angler-supplied data from tournaments and diaries kept by interested anglers were compared to data obtained from spring electrofishing surveys. Data on length-frequency distributions, mortality rates, and population estimates from the three methods were similar. Age-frequency distributions and growth rates derived from the electrofishing and tournament samples also were consistent. From creel surveys, electrofishing activities, tournaments, and examination of diaries, biologists were able to collect data at the rate of 1, 5, 15, and 40 fish per hour, respectively. This study demonstrated that large amounts of reliable data on a largemouth bass population can be obtained economically from volunteer anglers.