Age, Growth and Condition of Largemouth Bass, Micropterus salmoides, of Lake Ashbaugh, Arkansas

The population size structure, length at age and condition of 140 largemouth bass, Micropterus salmoides, were studied for Lake Ashbaugh, Arkansas. Scales and otoliths were used for age and length at age determination of individual bass. Length at age was determined by back-calculation and relative weight was used to measure condition. The Lake Ashbaugh population is dominated by young, slow growing bass in poor condition. Ninety-one percent of the largemouth bass in Lake Ashbaugh were less than four years of age, with age 3+ bass serving as the dominant year class. Proportional and relative stock density values were 25 and 3 %, respectively, significantly less than those of other surveyed Arkansas reservoirs. The mean relative weight for this population was 84, significantly less than that projected for healthy populations. Mean back-calculated lengths for largemouth bass ages I through age III were 141 mm, 190 mm, and 257 mm, respectively. Mean lengths at each age were significantly less than those obtained from a 1987 study of Lake Ashbaugh bass and for bass in other Arkansas reservoirs. Several factors may have contributed to the steady decline in the bass population of Lake Ashbaugh. Winterkills occurred in 1989-1991, which seemed to affect mostly mature largemouth bass. A380 mm length limit imposed in 1987 may have resulted in a stockpiling of bass less than 380 mm, increasing the competition for available prey for those size classes. These hypotheses are supported by consistent yearly declines over the past five years in the available prey/predator ratios and relative weights, particularly for the size classes between 226 mm-350 mm.