The Chesapeake Bay river herring migration study uses acoustic telemetry to track migrations of river herring tagged on spawning grounds in Chesapeake Bay tributaries.

The project will provide crucial information on the annual migration cycle from individual rivers to open ocean, supporting efforts to rebuild stocks of this economically, ecologically, and culturally important species group.

River herring is the common name for two species: alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis). These species are anadromous, meaning that they spend their adult lives in the ocean and migrate into freshwater rivers and streams to spawn.

River herring were once abundant in Chesapeake Bay, making up an important food source for wildlife and people alike. Overfishing, habitat fragmentation due to dams and other impediments to migration, and habitat degradation have resulted in sharp declines in river herring populations. These declines have caused tremendous economic and cultural loss, limiting fishing revenue and threatening fishermen’s way of life. Despite a moratorium on river herring fishing and extensive fish passage improvements in the bay and its tributaries, populations have struggled to rebound. Because of their migratory nature, the challenges that Chesapeake Bay river herring face today may be happening hundreds of miles from the bay.

Acoustic telemetry is a powerful tool that can provide information on the migrations of individual fish throughout their annual migration. A paper published in 2024 as a part of the project was the first to track habitat use of individual alewife throughout their entire migration. Alewife tagged in the Choptank River, MD were tracked as far north as the Gulf of Maine and Bay of Fundy, Canada, passing through most of the footprint of the Atlantic Cooperative Telemetry Network and venturing into the neighboring Ocean Tracking Network.

The results of the project have important management implications for river herring. Their migration takes them through waters which are undergoing rapid warming, across multiple fisheries management jurisdictions, and through regions with potentially high levels of incidental bycatch. Understanding their migratory patterns and timing provides fishery managers with new information to support actions that protect the fish along their journey.

Ongoing and future studies track both alewife and blueback herring from multiple Chesapeake Bay tributaries. As of May 2025, 450 river herring have been tagged in the Choptank, Patapsco, Potomac, and Rappahannock rivers.

The project is conducted by the Smithsonian Environmental Research Center, in collaboration with the Rappahannock Tribe and George Mason University. Funding was provided by the Smithsonian Institution Office of the Under Secretary for Science, NOAA National Marine Fisheries Service and National Fish and Wildlife Foundation. For more information, visit ACT Network projects CBALE, CBRIVERS24, and RAPPTRIBE.