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

Massachusetts Project

Evaluating freshwater productivity and sampling approaches for juvenile river herring in freshwater lakes and ponds

January 2015 - December 2017


Participating Agencies

  • Massachusetts Division of Marine Fisheries
  • National Fish and Wildlife Foundation

Anadromous alewife (Alosa pseudoharengus) populations have experienced alarming declines during the last two centuries. Seasonal migration and a unique life history has left them vulnerable to continued anthropogenic effects/events like habitat degradation, bycatch at sea and disrupted access to critical spawning rivers due to dams. Alewife provide vital marine-derived nutrients to freshwater systems, contribute as a prey-base for various piscivorous species and have strong cultural significance among coastal communities. To date, most population assessments are a function of adult run counts as they enter spawning habitats and data associated with freshwater juvenile productivity is lacking. Information gaps exist on the relationship between these adult spawning stocks and recruitment. Reliable abundance estimates hinge on accurate early life history data and remains a challenge. Our research objective is two-fold: evaluate factors influencing freshwater productivity and compare standardized and cost-effective survey-methodology to be applied across systems. A survey of 20 coastal lakes sampled in Massachusetts in 2014 will be expanded geographically to include nursery lakes with known alewife runs in Connecticut, Rhode Island, New Hampshire and Maine. Each lake will be sampled using purse seines and sonar imaging three times throughout the summer of 2015 for alewife young of year. We will assess juvenile densities, age and growth and mortality rates along with environmental predictors of nursery habitat. By testing novel methods of estimating alewife cohort dynamics we will compare/evaluate the legitimacy of these metrics to predict population size. Our results will help inform future population models and provide direction for habitat restoration and management decisions