DPS and population origin of subadult Atlantic Sturgeon in the Hudson River

Abstract

Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus is listed under the U.S. Endangered Species Act as five Distinct Population Segments (DPS). Subadult Atlantic Sturgeon are highly migratory in coastal waters and often move to non-natal estuaries where they encounter a variety of anthropogenic disturbances that may compromise their survival. The Hudson River estuary hosts large numbers of subadult Atlantic Sturgeon seasonally, but their DPS and population origin is unknown. We used microsatellite DNA analysis at 11 loci and sequence analysis of the mitochondrial DNA control region in Individual Based Assignment testing to determine the origin of 148 subadult Atlantic Sturgeon that were collected in the tidal Hudson River estuary between river kilometers (RKM)5 and RKM 124 north of the Battery in New York City (RKM 0). We also determined the origin of eight dead specimens (subadults and adults) that were likely victims of vessel strikes and found floating between RKM27 and RKM60. We determined that 142 of 148 subadults assigned to the Hudson River (New York Bight DPS), the vast majority (138 of 142) with at least 95%, and usually, 100%, probability. All eight dead specimens assigned to the Hudson River with greater than 99% probability. Of the six subadult specimens that did not assign to the Hudson, two each assigned to the Kennebec River (Gulf of Maine DPS) and Delaware River (New York Bight DPS), one to the Ogeechee River (South Atlantic DPS), and one to the James River (Chesapeake Bay DPS). Our analysis allows the effects of anthropogenic threats in the Hudson River to be apportioned to the DPS and natal river populations of Atlantic Sturgeon found there and serves as a model for genetic population composition analysis for subadult Atlantic Sturgeon in other impacted estuaries.