Introduction of fish species to North American drainages has occurred for over 100 years. Introduced fish species have been documented to have adverse effects on both the environment and native species of the drainage into which they have been introduced. To better understand the effects that introduced species may have on a particular drainage, it is essential to understand aspects of the introduced species’ life history. The objectives of the current study is to quantify the age, reproduction, growth, condition and diet of the yellow bass, Morone mississippiensis, in Barren River Lake, Kentucky. Monthly collections from three areas on Barren River Lake were made via a boat-mounted electrofisher from March 2008 to March 2009. Fish age was estimated by examining the sagittal otoliths of each individual. Reproductive condition was assessed using the mean gonadosomatic index (GSI) of all sexually mature individuals by month. Yearly growth rates were estimated by computing the mean length at age for each age class and subsequent calculation of the von Bertalanffy growth function (VBGF). To estimate the condition of yellow bass as it changed throughout the sample period, relative weight of each individual was calculated and the mean monthly relative weight was calculated. To examine the diet of yellow bass, diet items were identified to the lowest practical taxonomic level. Then, dry weight of each diet item was estimated and pooled by season to assess the season changes in the diet of yellow bass. Individuals of age group 3 were the most frequent. Mean GSI was significantly higher in March, April and May of 2008. Calculation of the VBGF yielded 254.7 mm as the maximum attainable mean total length of yellow bass in Barren River Lake. VBGF predicted mean total lengths of age classes 0-8 were as follows: 21.7 mm, 64.4 mm, 99.2 mm, 127.7 mm, 151.0 mm, 170.0 mm, 185.5 mm, 198.2 mm, and 208.5 mm. Relative weight was highest in summer. The diet of adult and sub-adult yellow bass relied heavily on chironomid larvae and pupae throughout the year, although diet item consumption was very low in winter. Young-of-year gizzard shad (Dorosoma cepedianum), however, became the most important adult diet item in the spring and summer. To better understand the impacts that the introduced yellow bass has on the ecosystem of Barren Rive Lake, a multi-year study including an estimation of relative abundance is recommended.

White bass Morone chrysops are native to the Mississippi River and its tributaries. This range includes the Barren River in south central Kentucky. Over the last thirty years, the population of white bass in Barren River Lake, a reservoir of the Barren River, has been in decline. During that same time, two congeners of white bass have been introduced to the lake. Hybrid striped bass Morone chrysops × Morone saxatilis were introduced in 1979 and yellow bass Morone mississippiensis were first discovered in 2000. Due to the similar life histories and spawning strategies of all three Morone species, I hypothesized that the two introduced species are interfering with reproduction of the native white bass. In the springs of 2012 and 2013 I sampled fish from within a five kilometer stretch of Barren River upstream of the lake. I collected 144 white bass, 111 yellow bass and 29 hybrid striped bass. Detection of species at spawning sites was staggered with yellow bass and hybrid striped bass arriving after white bass but leading to a period of co-occurrence. White bass on the spawning sites appeared healthy: fecundity (75,200 to 741,150 eggs per female), mean gonadosomatic indices (peaked at 10.7% and 23.7% in sequential years), mean relative weight (93.8), and length at age (above the 50th percentile). Of the yellow bass stomachs examined, 21.6% contained fish eggs or larval fish. Based on arrival times and evidence of egg and larval fish predation, it is likely that yellow bass are directly impacting white bass spawning success through reproductive interference and the consumption of white bass offspring. Schoener’s index values revealed a significant degree of dietary overlap between white bass and yellow bass in larval fish, post larval fish, and arthropods (Cxy = 0.992,0.994, and 0.804, respectively), and between white bass and hybrid striped bass in arthropods (Cxy = 0.851). Information from this study may elucidate causes of the declining white bass population and aid in its management in Barren River Lake.