Understanding the Recruitment Dynamics of American Shad (Alosa sapidissima) in the Hudson River Ecosystem.

Chang, Hsiao-Yun, Yong Chen, Stonybrook University, Stony Brook, NY

The American shad (Alosa sapidissima) supported historically important commercial and recreational fisheries along the Atlantic from the early 1800s throughout the 20th century. However, the catches of American shad declined drastically from more than 20000 mt in the late 1890s to 124 mt in 2019 and the Hudson River American shad fisheries have been on moratorium since 2010. The American shad is a migratory species and exhibits natal homing for spawning. The Hudson River estuary provides important spawning and nursery habitats. The lack of recovery and continuous low recruitment of American shad stock in the Hudson River after more than 10 years moratorium calls for a study to identify potential factors in their spawning and nursery habitat that might limit the American shad survival rates in their early life stages. This study uses the data collected in the historical Long River Ichthyoplankton Survey in the Hudson River Biological Monitoring Program from 1974 to 2017 to evaluate several plausible hypotheses explaining the depletion of the Hudson River American shad stock. We evaluate the spatio-temporal variability in their spawning season and ground and identify impacts of environmental factors (e.g. water temperature and dissolved oxygen) on the dynamics of American shad in their early life history stages. This study improves our understanding of the recruitment dynamics of Hudson River American shad stock and provides critical information to inform the management leading to the recovery of this important stock.