Empirical Evidence of Fall Spawning by Atlantic Sturgeon in the James River, Virginia

Abstract

Due to overfishing and habitat alteration, the anadromous Atlantic sturgeon Acipenser oxyrinchus oxyrinchus is severely depleted across its historic range. The James and York rivers in Virginia are the two rivers comprising the Chesapeake Bay distinct population segment, where Atlantic sturgeon reproduction has been confirmed. It is widely recognized that Atlantic sturgeon spawn in the spring throughout their range; however, there is debate over whether they also spawn in the fall. To determine if Atlantic sturgeon spawn in the fall, independent of the spring spawn, large-mesh gill netting in the freshwater portion of the James River (above river kilometer 108) was conducted in the spring (April–June) and fall (August–October) for 3 years (2009–2011), resulting in the capture of 125 adult Atlantic sturgeon (three were recaptures) during the fall sampling, but none were captured during the spring. Field examination for sex and stage of maturity identified 106 mature males and one postspawned female. Sex was not determined for four fish, and due to time constraints, 11 were not examined. Forty mature males were externally tagged with Vemco^© ultrasonic passives tags and movements were monitored with a Vemco^© VR2W passive receiver array. Collection and tracking data showed that mature Atlantic sturgeon aggregate in the freshwater portion of the James River during the fall season, entering during August and out-migrating by the end of November. No tagged fish were detected in the freshwater area of the river during the subsequent spring months. Though James River Atlantic sturgeon may spawn in the spring, we suggest there is strong evidence for an independent fall spawn, which should be considered in future management and recovery actions.

Received February 8, 2012; accepted June 8, 2012

ACKNOWLEDGMENTS

We thank Douglas Clarke, Kevin Reine (U.S. Army Corps of Engineers, Engineer Research and Development Center), Albert Spells (U.S. Fish and Wildlife Service, Virginia Fisheries Coordinator), Charles Fredrickson (James River Association), Eric Hilton and Hank Brooks (Virginia Institute of Marine Science), George Trice, Kelly Place, and Jimmie Moore (Virginia watermen), Stephen McIninch, Geoff Austin, Paul Bukaveckas, Michael Fine, Will Isenberg, Briana Langford, Mac Lee, Rob Tombes, and Anne Wright (VCU), Matt Fisher (Department of Natural Resources and Environmental Control-Division of Fish and Wildlife), Martin Balazik (DuPont) for assistance with data collection and development. We thank Kenneth Sulak (U.S. Geological Survey) and anonymous reviewers for editing and improving this report. This is VCU Rice Center Contribution number 24.