Cooperative Fish and Wildlife Research Units Program: Massachusetts
Education, Research and Technical Assistance for Managing Our Natural Resources

Inter-annual variation in river herring densities presents challenges to understanding the effects of restoration on fish productivity. Many agencies are actively working to improve aquatic connectivity in coastal rivers, with the specific aim of restoring diadromous fish populations, including river herring. There are several recent and future dam removals in eastern Massachusetts that will likely benefit river herring, but there is currently no planned monitoring of freshwater productivity following dam removal. We propose to sample juvenile river herring in freshwater lakes for at least 5 years after dam removal to assess patterns of river herring recovery, while simultaneously sampling lakes with current natural runs to address the following questions:
(1) How do juvenile river herring densities and growth vary among years and in relation to lake specific and regional environmental conditions?
(2) How many years following dam removal does it take to restore juvenile river herring productivity to that of a natural run?
We will also continue to stock two lakes with river herring, where we know the exact number of adults entering the systems, to develop relationships between adult density and juvenile density and growth, and can control stock densities under different environmental conditions. These stocked lakes also provide opportunities to develop pedigrees and understand factors influencing reproductive success.