Estimated Survival of Subadult and Adult Atlantic Sturgeon in Four River Basins in the Southeastern United States

William C. Post,Michael Loeffler,Joseph E. Hightower,Douglas L. Peterson

doi:10.1080/19425120.2015.1088491

Abstract

AbstractPrompted by concerns about the status of Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus, in 2012 the National Oceanic and Atmospheric Administration listed one distinct population segment (DPS) as threatened (Gulf of Maine) and listed the remaining four DPSs as endangered (New York Bight, Chesapeake Bay, Carolina, and South Atlantic). To provide information for recovery planning, we estimated the survival of subadult and adult Atlantic Sturgeon in two river basins within the Carolina DPS (Roanoke and Cape Fear rivers, North Carolina) and two basins within the South Atlantic DPS (Ashepoo–Combahee–Edisto rivers [ACE], South Carolina; Altamaha River, Georgia). Estimated detection probability varied strongly by season but was similar among river basins, likely reflecting a winter migration into marine waters with minimal receiver coverage. Apparent monthly survival was very high and precisely estimated for the Roanoke River (0.985; 95% credible interval [CI] = 0.970–0.995), Cape Fear River (0.979; 95% CI = 0.971–0.986), ACE (0.989; 95% CI = 0.979–0.993), and Altamaha River (0.985; 95% CI = 0.973–0.994) basins. A pooled estimate for 87 adults from all four basins was 0.988 (95% CI = 0.982–0.992). The monthly rates implied annual apparent survival rates of 0.839 (Roanoke River basin), 0.778 (Cape Fear River basin), 0.871 (ACE basin), and 0.842 (Altamaha River basin); the pooled estimate for adults was 0.860. Our estimated survival rates were similar to other recent estimates for Atlantic Sturgeon but lower than recent estimates for several populations of Gulf Sturgeon A. oxyrinchus desotoi. Recovery of Atlantic Sturgeon in these southeastern rivers will occur more quickly if survival can be increased to a level that is consistent with published estimates of true natural mortality (0.03–0.07; annual survival ≥ 0.93).Received March 18, 2015; accepted August 26, 2015

Highlights

Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus occur along the East Coast of North America, with known spawning populations from the St
The transmitters were detected by using fixed arrays of VEMCO VR2W submersible receivers that were deployed in riverine and estuarine waters of four basins: the Roanoke River, North Carolina; Cape Fear River, North Carolina; Ashepoo–Combahee–Edisto rivers (ACE), South Carolina; and Altamaha River, Georgia
Estimates of detection probability for April–October were relatively high in most cases, there were occasional low values during summer (e.g., Roanoke River, ACE, and Altamaha River basins in July 2011)

Summary

Introduction

Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus occur along the East Coast of North America, with known spawning populations from the St. Lawrence River, Quebec, to the Altamaha River or Satilla River, Georgia (Smith 1985; Wirgin et al 2000, 2007). Peterson et al (2008) obtained annual survival estimates of 0.79–0.83 for adult Atlantic Sturgeon in the Altamaha River based on a catch curve analysis of age data. We used telemetry to estimate the survival rates of Atlantic Sturgeon within several southeastern U.S rivers. Adult and subadult survival rates are key population parameters, so the availability of comparable but independent estimates from multiple rivers should be very useful in the planning of Atlantic Sturgeon recovery efforts. Our methods should be useful for application to other species with telemetry detections from marine and riverine receiver arrays

Methods

Results

Conclusion