Habitat Use of Striped Bass (Morone saxatilis) in the San Francisco Estuary and its Effect on Total Mercury and Heavy Metal Body Burden upon Capture

Striped Bass (Morone saxatilis) is a nearshore, anadromous fish in the San Francisco Estuary (SFE). A notable aspect of Striped Bass populations in general is yearly migrations, but there has been considerable disagreement over the homogeneity of these movements within the SFE. Additionally, since Striped Bass spend their entire lives in estuarine and nearshore environments, they likely encounter contaminants due to their proximity to anthropogenic pollution sources, a known concern with this species. The purpose of this study was to clarify habitat use, movements of Striped Bass in the SFE, and potential dangers to Striped Bass and consumers from contaminants by utilizing two sets of analyses, presented in separate chapters. Otolith microchemistry analysis was used to provide evidence of freshwater residency, identify distinct groups within the SFE system, and determine if ontogeny and gender affect movements and habitat utilization. Tissue chemistry analysis was then used to determine metal concentrations in Striped Bass fillets and examine correlations between these concentrations and habitat use. These analyses clearly show that resident subpopulations exist in the SF Delta and that yearly migrations are rare. Additionally, though almost all metals were below human consumption screening levels for contaminants, a few concentrations (mercury, selenium, and cadmium) in fillets were of concern.