Science Serving Maryland's Coasts
David Secor, Ph.D.
Chesapeake Biological Laboratory
Spatial Variation in Age, Growth, and Mortality of White Perch (Morone americana) Across Estuaries of the Chesapeake Bay
Management of white perch (Morone americana) populations in the Chesapeake Bay requires knowledge of demographic parameters, including age, growth and mortality. Spatial variation in vital rates may be genetically based, the result of differences in habitat or harvest across populations, or some interaction of these factors. Age was determined by examination of otolith thin-section, growth was analyzed using von Bertalanffy growth model, and mortality estimated through catch-curve analysis. Comparisons of vital rates were made within and between populations occurring in the James, York, Potomac, Patuxent, and Choptank rivers. Growth of white perch from the James, Patuxent, and Choptank rivers were best fit by sex-specific models, whereas growth of York and Potomac river white perch was best described by models including both sexes combined. Across rivers, growth was best described by separate Maryland (Potomac, Patuxent, and Choptank rivers) and Virginia river models (James and York rivers). Similarities in growth within Maryland and Virginia rivers may be a function of connectivity between these populations or similarities in habitat. For most river systems, excluding the Potomac and Choptank, mortality was best estimated by sex-specific models rather than combined sex models. Mortality was found to be similar across populations, however, bias in fish collection and violation of the assumptions of catch-curve analysis may have affected our estimates. Similarities in growth suggest that white perch populations in the Chesapeake Bay may benefit from management as two units (MD and VA rivers), however, further research is required to draw definitive conclusions.
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