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

In this study, we aim to “close the loop” in our understanding of river herring life stages and limits to productivity by collecting novel data on juvenile river herring density, growth, and survival in estuaries and information on river herring emigrating from lakes. Specifically, our objectives are to: 1)characterize density, growth, and mortality of juvenile river herring in estuaries and upstream lakes, 2) assess age, size, and timing of juvenile river herring during emigration from freshwater to estuarine habitats, and 3) evaluate relationships between spawning adults, juvenile abundance and timing of movements to identify conditions that promote growth and survival. We hypothesize that the timing of juvenile emigration from lakes, size at emigration, and growth in lakes and estuaries will vary among systems and will depend on river herring densities, habitat characteristics, and food resources. The new data collected will be incorporated into a full life-cycle model developed by our collaborators at MADMF to inform the run dynamics and migration timing that leads to the best growth and maintenance of densities, and to inform our work linking life-stages in collaboration with project partners and a population model produced as part of that work. Modeling of factors controlling juvenile size and number during egress, combined with estimates of estuarine-marine survival and growth, will help close current gaps in knowledge of the river herring life cycle and allow for improved understanding of stock-recruitment relationships and population modeling efforts.