Age-0 Largemouth Bass Micropterus Salmoides Research Articles

Comparisons of Cove Rotenone and Electrofishing Catch-Depletion Estimates to Determine Abundance of Age-0 Largemouth Bass in Unvegetated and Vegetated Areas

ABSTRACT We compared cove rotenone sampling and Leslie catch-depletion estimates of age-0 largemouth bass (Micropterus salmoides) abundance in vegetated and unvegetated areas of Lake Guntersville, Alabama, in July—August 1992. With the Leslie catch-depletion method, bass abundance was estimated in 0.05 to 0.32-hectare areas enclosed with a block net. A 4.3-meter direct-current electrofishing boat was able to completely fish each enclosure with five to seven consecutive sampling runs and constant effort. Size-selectivity was not evident as no significant correlations existed between mean length and mean weight at capture for each sampling interval. In addition, catchability remained constant over time. In a cove that contained Eurasian watermilfoil (Myriophyllum spicatum), we estimated 1,088 age-0 largemouth bass/hectare from the two electrofishing catch-depletion samples compared to 1,386 bass/hectare by subsequent rotenone sampling. Cove rotenone density and biomass estimates in four unvegetated coves (1...

Movements by Young-of-Year and Yearling Largemouth Bass and Their Implications for Supplemental Stocking

Abstract Young-of-year (age-0) largemouth bass Micropterus salmoides from the Little Beaver Creek embayment of B. Everett Jordan Lake, North Carolina, were individually tagged with magnetic binary-coded wire tags in 1989 and 1990. Fish were recaptured during electrofishing and seine sampling in the year of tagging and the following year. In 1989, 529 age-0 largemouth bass were tagged, of which 40 were recaptured. Of these, only 2 of 31 age-0 and 2 of 9 yearling fish had moved out of their tagging coves. In 1990, 1,090 age-0 largemouth bass were tagged, of which 47 were recaptured. Of 15 recaptured largemouth bass that had been tagged in coves, only 2 age-0 fish had moved from their tagging coves. Of 32 recaptured largemouth bass that had been tagged outside coves, only 2 age-0 and 1 yearling fish had moved into cove areas. No tagged age-0 or yearling largemouth bass were recaptured outside the embayment. Because most fish seem to stay near their tagging site, localized supplemental stocking of fingerlings...

Length-Dependent Winter Survival and Lipid Composition of Age-0 Largemouth Bass in Bay Springs Reservoir, Mississippi

Age-0 largemouth bass Micropterus salmoides were studied in Bay Springs Reservoir, Mississippi, to determine if the larger young had greater survival through their first winter and if this survival was influenced by levels of energy reserves. Abundance decreased from 542 young/ hectare in June, when fish averaged 37 mm total length, to 12/hectare in March, when lengths averaged 149 mm. The length-frequency distribution of this year–class was positively skewed during June–August, became bimodal during September–January, and lost most of the smaller mode by March. During September–January, fish in the smaller mode decreased in abundance from 176 to 9/hectare and their mean length remained near 60 mm; fish in the larger mode decreased in abundance from 76 to 27/hectare and increased in length from 108 to 154 mm. Whole-body lipid content increased from 3.5% of dry body weight in fall to 5.9% in December and decreased to 3.3% in March. All young had equal amounts of stored lipid by late fall, but by March the surviving small young had less lipid than large young, suggesting that during winter smaller fish spent their reserves at a faster rate. Protein content averaged 74.6% of the dry body weight and neither differed among months nor changed with fish length. Mortality of the smallest young was accelerated in late fall and winter, coinciding with decreases in lipid stores and rapid drops in water temperature.

Use of a Catch-Depletion Method to Estimate Population Density of Age-0 Largemouth Bass in Submersed Vegetation

Abstract A Leslie catch-depletion method was used to estimate abundance of age-0 largemouth bass Micropterus salmoides in submersed aquatic vegetation. Four 0.11-hectare areas were enclosed with a block net in stands of Eurasian milfoil Myriophyllum spicatum. Young largemouth bass were removed during six to seven successive 10-min intervals by use of DC electrofishing gear. Over time, catch per effort declined linearly with cumulative catch by an order of magnitude. Age-0 largemouth bass population density estimates from the four enclosures were similar to those obtained in a 1.2-hectare vegetated cove treated with rotenone. Catchability coefficients, or the slopes of the regressions between catch per effort and cumulative catch, were similar among enclosures and remained relatively constant over successive electrofishing intervals. The coefficient of variation for mean density, derived by using the catch-depletion method, was 42%, similar to values typically associated with rotenone sampling. This catch-...

Relationships among Fat Content, Condition Factor, and First-Year Survival of Florida Largemouth Bass

Major reductions in abundance of age-0 largemouth bass Micropterus salmoides (76–87%) occurred between May and June (1981) or between June and July (1980, 1982) in Lake Dora, Florida. The severity of this mortality was not consistently related to spawning success, as measured by densities of age-0 fish in spring block-net samples before the periods of heavy mortality. High-mortality periods typically coincided with diet shifts towards piscivory. Age-0 largemouth bass exhibited the least piscivory at the same time that biomass ratios of available fish prey to predators were lowest in the two years (1980, 1981) they were measured. The lowest observed prey: Predator ratios also preceded periods of major mortality. This period of density reduction was accompanied by a significant reduction in percentage fat of age-0 fish in 1980 and 1982, but not in 1981. The major reductions in density of age-0 largemouth bass between May and July were believed to represent a survival bottleneck that should be considered in conjunction with stock assessment and management efforts directed at this species.

Day-to-Day Variation in Food Consumption by Largemouth Bass

Abstract Substantial day-to-day variation in food consumption by groups of laboratory-held age-0 large-mouth bass Micropterus salmoides occurred at temperatures of 14, 20, and 26 C for 108–113- and 136–140-mm size classes of fish. The largemouth bass were continuously provided with an unrestricted ration of live fathead minnows Pimephales promelas. Day-to-day differences in food consumption could not be distinguished from random variation about a mean value, indicating that day-to-day consumption levels were independent of each other. The effects of fish sample size on the number of sample dates needed to assure certain levels of precision in the estimation of mean diel food consumption over 5-week intervals (based on the feeding schedule of age-0 largemouth bass in the present study) were simulated by computer. A 95% probability of only a 10% relative error level (coefficient of variation) would require sampling 25 fish from two to four times over the 5-week period. Caution should be exercised when obser...