Juvenile Atlantic Sturgeon Habitat Use in Newburgh and Haverstraw Bays of the Hudson River: Implications for Population Monitoring

Abstract.—Populations of Atlantic sturgeon Acipenser oxyrinchus are at historically low levels along the Atlantic coast of North America. Atlantic sturgeon is a long-lived species with a complex life history, making population assessment difficult. The purpose of this study was to determine seasonal habitat use by juvenile Atlantic sturgeon in the Hudson River estuary and provide recommendations for future population monitoring. Our study focused on Newburgh and Haverstraw bays in the Hudson River, as these are areas of known juvenile sturgeon concentrations. The habitat within each bay was coarsely stratified according to substrate (hard versus soft) and depth (deep versus shallow). Sampling occurred during fall 2003, spring and fall 2004, and spring and fall 2005. Fall sampling occurred from October through November and spring sampling occurred from March through April. We used anchored gill nets of 76-, 102-, and 127-mm stretch mesh fished together at a sampling site. A total of 562 individual juvenile Atlantic sturgeon were captured during the course of this study (14 were captured more than once), the majority (90%) coming from Haverstraw Bay. Soft and deep habitat comprised only 25 % of the available habitat in Haverstraw Bay but yielded the greatest frequency of catches, the highest mean catch per unit effort (CPUE), and lowest variance of CPUE. Catch per unit effort was highest during spring seasons in soft–deep areas of Haverstraw Bay. These results suggest that future population monitoring should focus sampling effort in soft–deep areas o