Master of Science (M.Sc.)
Virginia Institute of Marine Science
Striped bass (Morone saxatilis) and white perch (M. americana) are two common species residing within Chesapeake Bay and its tributaries. These congeners are both commercially and recreationally important species. White perch are permanent residents in the Bay, while striped bass are only residents during the first few years of their life. During these initial years, striped bass co-occur with white perch. There is very little known about white perch and resident striped bass site fidelity and home range. This acoustic tagging study aims to examine site fidelity and home range of both species and determine if there is any spatial competition between these congeners.
Sixteen white perch and sixteen striped bass residing in two small tributaries of the York River were utilized for this experiment. White perch exhibited a high degree of site fidelity along with a small home range. The minimum convex polygon (MCP) and minimum stream polygon (MSP) methods were utilized to measure home range size. The average MCP/MSP was 0.114 km2. Kernel densities were also examined to understand their utilization distribution within their home range. The output contours considered were the 95% contour (total home range) and the 50% contour (core area of activity). The kernel method areas were 0.0128 km2 and 0.0021 km2, respectively. White perch, in the Poropotank River, typically had two core areas of activity which often correlated to the tidal stage. They were often found during high tide upon the flooded marsh or up in shallow creeks and in the relatively deep main channels during low tide. However, white perch in the Queen Creek only had one core area of activity and they were always associated with submerged structure. White perch did not show any movement with sudden changes in salinity and/or temperature resulting from tropical depressions or Hurricane Isabel. They also did not display any change in behavior associated with episodic hypoxia within the creeks.
Striped bass did not exhibit a high degree of site fidelity. In the Poropotank River, 58% of the striped bass displayed site fidelity, while zero striped bass exhibited it in Queen Creek. Local hypoxia events could explain the lack of site fidelity within Queen Creek. The home range data might be under-estimated due to the inability to track in the York River. The average MCP/MSP was 0.36 km.2 and the average 95% and 50% kernel densities were 0.02 km2 and 0.002 km2, respectively. Only two striped bass displayed a tidal interaction, utilizing the slack high water to flood up upon marsh corners or sandy beaches. Two other striped bass also displayed a lunar periodicity. Both fish would enter and leave the Poropotank River during the days surrounding new and full moons. Striped bass also did not display any change in behavior associated with sudden changes in temperature and/or salinity due to tropical depressions or Hurricane Isabel.
There was very little space competition between these two congeners. White perch occupied 8.5% of the striped bass overall home range. The spatial overlap did increase when only core areas were examined. The two species shared a common core area in a small rivulet of the Poropotank River. This common core area was one third of the striped bass cumulative core area. Nevertheless, there very little evidence of spatial competition or resource partitioning between white perch and striped bass.
© The Author
McGrath, Patrick E., "Site Fidelity, Home Range, and Daily Movements of White Perch, Morone americana, and Striped Bass, Morone saxatilis, in Two Small Tributaries of the York River, Virginia" (2005). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1539617830.