Restoring the habitat of the American Shad

American Shad, whose scientific name, Alosa sapidissima, means “most delicious of herrings,” have been a source of food for those living along their native East Coast, from Newfoundland to Florida, for generations.

While not classified as an endangered species, the American Shad population declined significantly during the 20th century and remains low, a consequence of poor water quality and dams that block their paths to historic spawning grounds.

The Watershed Institute, a nonprofit whose mission is to protect and restore central New Jersey’s water and natural environment, hosted a webinar on March 27 to discuss the long history of the American Shad and the institute’s efforts to restore their habitat.

“The mission of the organization has remained pretty much the same for 75 years,” said Jim Waltman, executive director of institute. “We exist to keep your water clean, safe and healthy, protecting and restoring our local environment through conservation, advocacy, science and education.”

Waltman was one of the webinar’s keynote speakers, along with Clay Emerson, a water resource engineer and senior technical director at Princeton Hydro, an engineering firm that develops solutions for watershed management and ecological restoration.

American Shad spend most of their lives at sea but return to rivers during the spring. 

“One of their most noteworthy characteristics is this amazing migration,” Emerson said. “They spawn in our rivers but live most of their life in the ocean.”

During their time in freshwater, American Shad take up a place in the food chain, preying on aquatic insects and serving as prey for larger fish and birds like gar and osprey. The camouflage American Shad have evolved to defend against predation makes them difficult to spot.

“If you’re a person standing at the water’s edge, I challenge you to point out a shad,” Emerson said. “They’re not in the business of being seen.”

Efforts to remove dams

According to Emerson, around 40 percent of the American Shad’s historic habitat is currently inaccessible to them. The Watershed Institute has been seeking to remove obsolete dams in central New Jersey to open up local rivers for the shad during spawning season. 

The institute’s most recent success was the removal of the Weston Mill Dam in 2017, which opened up a 4.5-mile span of the Millstone River to migratory fish. The spring after the dam was removed, American Shad were observed in the stretch of river beyond the former dam by the U.S. Fish and Wildlife Service.

The Watershed Institute has turned its attention to the Blackwells Mills Dam, upstream of the former Weston Mill Dam. Its removal would open up an additional nine miles of the Millstone River to American Shad and other migratory fish.

While the institute says its project has the support of the NOAA-Fisheries Service, N.J. Division of Fish and Wildlife, N.J. Office of Natural Resource Restoration, and N.J. State Park Service, it has hit a snare in a disagreement with the United States Geological Survey’s New Jersey office.

The USGS maintains a flow gauge that collects data just upstream of the Blackwells Mills Dam.

“The USGS believes that the dam makes for more precise and accurate information on the flow of water in the river than if the dam were to be removed,” Waltman said.

While Waltman and the Watershed Institute acknowledge that the data gathered by the flow gauge is important, they still advocate for the dam’s removal. They argue that the agency will be able to collect accurate data, pointing to a similar dam removal in Pennsylvania’s Jordan Creek.

“There was a USGS flow gauge behind that dam,” Waltman said. “The dam was removed. The gauge was recalibrated and the data collection is considered by the agency to be as accurate and as precise as it was before when the dam was there.”

American Shad remain an important part of the heritage of the regions they return to annually. 

Lambertville, N.J., is home to Lewis Fishery, the only commercial shad fishery on the non-tidal Delaware River in the state, and hosts an annual “Shad Fest” every year in April, where residents and visitors celebrate the past and present significance of the fish to their lives and culture.