Evaluating fish passage at the Island Farm Weir on the Raritan River

The Raritan River has experienced a wide variety of human impacts from pollution to development and dam building. However, water quality has improved and, in the past couple years, three dams have been removed. Dam removal should provide access to new spawning habitat for fish like American shad and river herring. These anadromous species return from the Atlantic Ocean every spring to spawn in the Raritan River where they were born.

One remaining obstacle for migrating fish is the Island Farm Weir in Bound Brook, NJ. This low head dam just downstream from the confluence of the Raritan and Millstone rivers is equipped with a fish ladder.

Carl Alderson and Olaf Jensen tag an American shad.
Carl Alderson (left, NOAA) and Olaf Jensen (right, Rutgers) tag an American shad. Photo credit: Orion Weldon

To evaluate how well the fish ladder is working, Rutgers scientists and students are tagging shad and river herring below the dam and monitoring their progress.

These electronic tags are slightly smaller than a tylenol pill and function like EZPASS for fish. When a tagged fish passes through an antenna at the fish ladder entrance and exit, the time, date, and tag number are recorded. A video camera in the fish ladder viewing room records all fish that pass through the ladder, day or night, tagged or untagged.