The iconic shad, a fish that fed George Washington’s army and sustained later generations of Americans, is breeding in the Delaware River in numbers not seen in almost four decades, indicating that water quality has improved and dams have been removed to allow many more of the fish to return to their spawning grounds.
The New Jersey Department of Environmental Protection said Monday that the number of juvenile shad counted at various location in the Upper Delaware this summer was at its highest in 38 years of monitoring. The approximately 24,500 young shad were about three times as many as a year earlier, and almost 10 times the number recorded in 2013.
In this year’s spring shad run, when fish return from the ocean to spawn in the river’s shallow upstream water, the total number of fish recorded at a fishery in Lambertville, Hunterdon County, was 1,262, the ninth-highest in 92 years, the DEP said.
At another location in Hunterdon County, the number of shad caught by netting this summer exceeded that for the last five years combined.
The numbers represent a strong recovery after sharp declines for the species in the 1950s and 1960s, when heavy pollution slashed oxygen in the lower river near Philadelphia to a level that stopped many fish swimming upstream to spawn.
Since then, tighter controls on wastewater treatment plants and sources of industrial pollution have allowed oxygen levels to recover to the point at which the fish are returning in numbers not seen in years.
The fish have also been helped by the removal of dams that previously prevented them from swimming upstream to spawning grounds. With those barriers removed, the shad are now able to return to the upper river and its tributaries, especially the Musconetcong River, the DEP said.
Further, their recovery has been helped by the closure of commercial shad fisheries in the ocean in response to stocks falling to an all-time low, officials said.
“The strong shad-spawning run and record-setting juvenile numbers this summer lead us to be very optimistic about the future of shad, a species that is important to the overall ecological health of the Delaware River,” said DEP Commissioner Bob Martin, in a statement.
Shad play an important role in the river’s ecology, as food for bigger fish and other predators such as birds. Some wildlife species time their migrations to coincide with the shad run.
The fish have also played an important role in the history and economy of the Delaware basin, feeding native Americans, sustaining George Washington’s Continental Army, and supplying a major commercial fishery in the 19th century, helping to support the region’s growing population.
The Delaware River Basin Commission, an interstate regulator that manages water flows and quality in the 330-mile-long watershed, welcomed the shad’s recovery as a sign of improved health for the river as a whole.
“Historically, American shad have spawned in the main Delaware River, as well as in several of its tributaries,” said DRBC spokesman Clarke Rupert. “Today, the Delaware River continues to support American shad, thanks in part to the absence of dams on the main stem river and to water quality that has seen significant improvement over the years due to efforts of DRBC and other agencies and stakeholders.”
Despite the improvement, there is still work to be done to restore the shad population to levels seen before the river’s quality was badly damaged in the 1950s and 1960s, said Maya van Rossum of the environmental group Delaware Riverkeeper Network.
Van Rossum welcomed the increasing numbers, which she said are the result of decades of work to improve water quality, but said current shad numbers don’t yet match the millions that previously lived in the river.
By comparison, the current population is probably measured in the hundreds of thousands, representing progress but not a full recovery, Van Rossum said. “This is a really important sign of progress for the restoration effort,” she said. “It certainly shows that things are going in the right direction.”
The recovery argues for continued strong protections for the river rather than a “regulatory rollback” at state and federal level that van Rossum fears would weaken protections for water quality and the fish that depend on it.
“This is a good sign that all the investments that we’ve been making in trying to do those things is value added,” she said. “It makes a difference for the fish, and it makes a difference for the people who care about and rely on the fish.”