Origin of Atlantic Sturgeon Collected off the Delaware Coast during Spring Months

Abstract

Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus was federally listed under the U.S. Endangered Species Act as five distinct population segments (DPS). Currently, at least 18 estuaries coastwide host spawning populations and the viability of these vary, requiring differing levels of protection. Subadults emigrate from their natal estuaries to marine waters where they are vulnerable to bycatch; one of the major threats to the rebuilding of populations. As a result, identifying the population origin of Atlantic Sturgeon in coastal waters is critical to development of management plans intended to minimize interactions of the most imperiled populations with damaging fisheries. We used mitochondrial DNA control region sequencing and microsatellite DNA analyses to determine the origin of 261 Atlantic Sturgeon collected off the Delaware coast during the spring months. Using individual-based assignment (IBA) testing and mixed stock analysis, we found that specimens originated from all nine of our reference populations and the five DPSs used in the listing determination. Using IBA, we found that the Hudson River population was the largest contributor (38.3%) to our coastal collection. The James (19.9%) and Delaware (13.8%) river populations, at one time thought to be extirpated or nearly so, were the next largest contributors. The three populations combined in the South Atlantic DPS contributed 21% of specimens; the Altamaha River, the largest population in the South Atlantic DPS, only contributed a single specimen to the collection. While the origin of specimens collected on the Delaware coast was most likely within rivers of the New York Bight DPS (52.1%), specimens that originated elsewhere were also well represented. Genetic analyses provide a robust tool to identify the population origin of individual sturgeon outside of their natal estuaries and to determine the quantitative contributions of individual populations to coastal aggregations that are vulnerable to bycatch and other anthropogenic threats.

Received March 17, 2014; accepted September 3, 2014

ACKNOWLEDGMENTS

We thank New York Sea Grant (Grant R/SG-20) and the Molecular Facility Core of the NYU National Institute of Environmental Health Sciences Center ES00260 for their support. Funding for our coastal sampling program was provided by the National Marine Fisheries Service's Anadromous Fish Conservation Act (NOAA Award NA08NMF4050611, NOAA-NMFS-NERO contract EA133F-08-CN-0151) and Species Recovery Grants to States (NOAA Award NA10NMF4720030) project. We acknowledge the statistical assistance of Arthur Nadas. We thank Lori Brown for her assistance with database management and sampling handling, as well as Michael Lohr for his assistance during field collections. Atlantic Sturgeon sampling following their ESA listing was carried out under the auspices of National Marine Fisheries Service research permit 16507. Prior to listing Atlantic Sturgeon were sampled under annual state of Delaware collection permits. The use of trade names does not imply endorsement by the U.S. Government.