Over the last decade, American shad abundance in the Potomac River has continued its consistent rise, driving the overall upward trend of shad abundance in the Chesapeake Bay.
The Chesapeake Bay Program tracks the abundance of this forage fish in the James, Potomac, Rappahannock, Susquehanna and York rivers as an indicator of watershed health. Collectively, these five waterways account for about 90 percent of the Bay’s shad population, and each has its own population target. Targets in the Susquehanna and upper James rivers are based on the amount of shad certain segments of these rivers can support, while targets in the Potomac, Rappahannock, York and lower James are based on historic population levels.
Overall, shad abundance in the Chesapeake Bay increased from 9 percent of the goal in 2000 to 41 percent of the goal in 2013. The Potomac River has seen the most consistent increase in returning shad, which spend their adult lives in the ocean but migrate into freshwater rivers and streams to spawn: between 2000 and 2013, shad abundance in the Potomac rose from 12.4 percent to 129.4 percent of the target. Scientists attribute this dramatic increase to a series of factors, including improvements in water quality; a resurgence in underwater grass beds; the installation of a fish passageway at Little Falls Dam; a moratorium on recreational shad harvest; stocking efforts that reprinted fish to the river and kick-started the population; and the overall suitability of the Potomac as shad habitat. The river was once so full of shad in the spring that onlookers said it ran silver.
While shad abundance is also relatively high in the Rappahannock River—reaching 92.7 percent of the target in 2012 but falling to 88.9 percent of the target in 2013—abundance remains negligible in the upper James and Susquehanna and variable in the lower James and York. Some variability is natural, but the continued scarcity of shad in the upper James and Susquehanna can be attributed to large dams that block fish passage and mute some of the natural cues that send migratory fish upstream.
Between 2000 and 2013, American shad abundance in the Chesapeake Bay increased from 9 percent of the goal to 41 percent of the goal. Over the long term:
American shad spend most of their adult lives in the ocean, migrating into the Chesapeake Bay’s freshwater rivers and streams each spring to spawn. Once one of the most valuable fisheries in the Bay, shad populations have declined in recent decades due to pollution, historic overfishing and the construction of dams that block the fish from reaching their spawning grounds. Commercial shad harvest is now closed across most of the region, and Chesapeake Bay Program partners are working to remove dams, install passageways that allow shad to reach upstream habitats and restock waterways with hatchery-raised fish. In addition, students in Maryland, Virginia and the District of Columbia are raising shad and releasing them into the Potomac River, bringing public attention to the importance of the once-forgotten fish.
American shad form an important link in the Chesapeake Bay food web: shad feed on zooplankton, and in turn are eaten by larger fish like bluefish and striped bass. Shad are also part of the region’s history and culture, and many communities still hold spring shad festivals to celebrate the return of the fish.
“While there are several factors behind the shad recovery in the Potomac River, improved water quality is the cornerstone. Without cleaner waters in the Potomac River, we would never have seen such a boost in returning shad. We’ve reached the sustainable fishery target for the river, but we are still working to achieve a more robust goal: to see the shad population healthy and fit, and to see the river run silver again. That’s not a ‘pristine river’ goal—that’s a goal we can achieve.”
--- Jim Cummins, Director for Living Resources, Interstate Commission on the Potomac River Basin, and Co-Chair, Chesapeake Bay Program’s American Shad Indicator Action Team
“We appreciate the work of the Chesapeake Bay Program’s American Shad Indicator Action Team to refine the basis for evaluating the health of American shad, a critically important species in the Chesapeake Bay. The shad indicator helps us track benefits to shad at the watershed level thanks to habitat restoration efforts such as dam removals and fish passage projects.”
--- Peyton Robertson, Director, National Oceanic and Atmospheric Administration Chesapeake Bay Office, and Chair, Chesapeake Bay Program’s Sustainable Fisheries Goal Implementation Team