Influence of partial migration and environmental change on the population dynamics of white perch (Morone americana) within the Hudson River Estuary
Secor, David H
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White perch are a common estuarine fish that exhibit a complex life cycle, characterized by partial migration and sensitivity to ecosystem characteristics. Field collections, otolith microchemistry, otolith microstructure and environmental and biological monitoring data were used to investigate the prevalence of partial migration and environmental influence across life history stages of white perch within the Hudson River. Otolith strontium:calcium profiles identified a freshwater resident contingent and a migratory contingent which utilized brackish habitats. Demographic analyses indicated that migratory fish hatched earlier and experienced cooler temperatures as larvae compared to residents, and subsequently grew faster as juveniles and adults. Comparisons of early-life characteristics before (1974-1991) and after (1992-2013) the invasion of zebra mussels indicated that juvenile abundance became more sensitive to density-dependence and freshwater flow after the invasion, while growth and spatial distribution changed little. Partial migration and environmental sensitivity will shape Hudson River white perch responses to future climate change.