Handling and tagging effects, in-river residence time, and postspawn migration of anadromous river herring in the Hudson River, New York

Abstract

In a 2013 pilot study, acoustic tags were inserted into two species of river herring, Alewife Alosa pseudoharengus and Blueback Herring Alosa aestivalis. The primary objectives were to identify handling and tagging effects and assess in-river residence time. The secondary objective was to identify postspawn coastal migration patterns. Fish were collected on spawning grounds in the upper portion of the Hudson River, New York. Vemco V7 acoustic transmitters were gastrically inserted into 25 river herring (13 Alewives and 12 Blueback Herring) that were in pre, active, or post spawning conditions. In-river acoustic data were collected from 23 of the 25 river herring. The majority of tagged fish exhibited some level of fallback (downstream migration) after the tagging event, all Blueback Herring and all male Alewives returning to spawning areas. The majority of female Alewives did not return to the spawning area after tagging, and this may be a result of when and where tagging events occurred. Both species of river herring exhibited similar in-river residence times of approximately 2–3 weeks and exited the system 3–6 d after spawning. Information on coastal movements of four Blueback Herring (two females and two males) was also obtained, spanning the south shore of Long Island, New York, to the mouth of Penobscot Bay, Maine. Coastal and in-river tag detections were reported by members of the Atlantic Cooperative Telemetry Network. In conclusion, this experiment can now be repeated with confidence on a larger scale with multiyear tags in order to identify unknown in-river spawning areas, provide information regarding spawning site fidelity, and bolster current knowledge of coastal migration patterns for both species.