Trophic Niche and Diet Overlap between Invasive White Perch and Resident White Bass in a Southeastern Reservoir

The White Bass Morone chrysops is a popular sport fish that appears to be negatively affected by invasions of White Perch M. americana and often declines or disappears from invaded systems. In 2008, the first discovery of White Perch in Lake James, North Carolina, provided a rare opportunity to investigate trophic overlap between White Perch and a robust population of White Bass near the onset of invasion. We investigated the potential for resource competition between White Perch and White Bass by assessing their relative abundance (CPUE), trophic position, niche size, diet breadth, and diet overlap across 2 years. White Perch were more abundant than White Bass and had wider diet breadth and trophic niche size across seasons. White Perch also occupied lower trophic positions than White Bass, indicating that White Bass maintain a more piscivorous diet. However, diet and stable isotope analysis showed a high overlap between juvenile White Bass and all sizes of White Perch. Thus, juvenile White Bass may be susceptible to competition with White Perch where resources are limited. Therefore, biologists should take steps to prevent White Perch introductions into systems with popular White Bass fisheries. The White Perch Morone americana is a highly successful invasive species in lakes and reservoirs across the United States (Zuerlein 1981; Boileau 1985; Feiner et al. 2012), and White Perch invasions have been associated with declines in many native species (Hergenrader and Bliss 1971; Hurley and Christie *Corresponding author: [email protected] 1Present address: Department of Forestry and Natural Resources, Purdue University, 195 Marsteller Street, West Lafayette, Indiana 47907, USA. 2Present address: Arizona Game and Fish Department, 5000 West Carefree Highway, Phoenix, Arizona 85086, USA. Received October 19, 2012; accepted March 13, 2013 1977). The White Bass M. chrysops is a popular sport fish that appears to be especially affected by White Perch invasions, often declining or disappearing from invaded systems (e.g., Gopalan et al. 1998; Madenjian et al. 2000; Harris 2006). White Bass and White Perch rely on similar food resources throughout their ontogeny (Priegel 1970; Voigtlander and Wissing 1974; Prout et al. 1990; Wong 2002), although White Bass become primarily piscivorous as adults (Muth and Busch 1989; Hartman 1998) while adult White Perch continue to consume some zooplankton and benthic invertebrates (Gopalan et al. 1998; Wong 2002; Harris 2006). Previous studies have found moderate to high diet overlap between White Perch and juvenile White Bass (Gopalan et al. 1998; Madenjian et al. 2000; Kuklinski 2007). We suggest, therefore, that interspecific competition for resources may be driving White Bass declines in invaded systems. Recently, two North Carolina reservoirs, Lake Norman and Lake Hickory, experienced drastic declines in formerly abundant White Bass populations in the years following unintentional White Perch introductions (K. J. Hining, NCWRC, and B. J. McRae, NCWRC, personal communications) causing concern among biologists about the potential for declines in other systems. During routine North Carolina Wildlife Resources Commission (NCWRC) sampling in 2008, 35 White Perch were captured in Lake James, North Carolina. Subsequent sampling 912 D ow nl oa de d by [ N or th C ar ol in a St at e U ni ve rs ity ] at 0 6: 38 2 9 M ay 2 01 3