Environmental monitoring is crucial to the success of ecological research and restoration efforts.  Due to their decline throughout the eastern United States, two species of anadromous fish, blueback herring, (Alosa aestivalis) and alewife (A. pseudoharengus), collectively referred to as river herring, are considered important indicator species. Sustainable management of these species will require a monitoring effort to collect accurate data on the status of and trends in their populations. During their annual spring spawning migration, river herring ascend freshwater streams. Fishways deployed in these streams provide an opportunity to establish digital video camera monitoring stations. During their 8-week migration an adult river herring can pass through any monitoring station in minutes and most of the run will pass on any given day. Under these circumstances, conducting accurate counts is highly problematic.  Digital video cameras, coupled with wireless data-transmission technology, provide a low-cost, accurate, automatic monitoring system. The digital format enables automated computer image analysis. We implemented such a system for monitoring the movement of river herring, and evaluated the system’s performance in four coastal rivers in eastern Massachusetts.