Supporting Alewife Restoration in the St. Croix Watershed - Anadromous Fish Telemetry Assessments


Aquatic Ecosystem Health

Project Description


Since 1981, fish counting at the most downstream dam on the St. Croix River has provided a reliable annual estimate of the number of anadromous fish returning to the watershed. NB Power’s Milltown Dam at St. Stephen NB has been an ideal site to measure progress of international efforts to restore sea-run alewife, blueback herring and American shad in the St. Croix River watershed.  The IJC IWI program has supported these counts, biological analyses and other assessments that help inform future fish restoration planning, including a recent IWI-funded report entitled “Exploring Upstream and Downstream Fish Passage Improvements on the Lower St. Croix River”.

With increasing numbers of fish in the decade and potential for large scale restoration in the next few years and the upcoming decommissioning of Milltown dam, it is essential that the fish studies continue in cooperation with all partners. In 2022, and until Milltown Dam removal, fisheries assessments that include the fish counts, PIT (Passive Integrated Transponder) tagging, and radio telemetry are needed to inform population trends and provide actionable information for restoration planning needed throughout the watershed. To carry out this IWI work and assess the efficiency of fish passage, the St. Croix International Waterway Commission (SCIWC) has garnered approval from Woodland Pulp, LLC to install, maintain, and monitor antenna systems at the next three dams upstream of Milltown: namely the Woodland, Grand Falls, and Vanceboro dams. 

To assess current efficiencies of the fishways, the SCIWC has partnered with the Peskotomuhkati Nation at Skutik to provide PIT tag reader equipment and data analysis techniques using the R Program, as well as the Passamaquoddy Nation at Indian Township to monitor movement readers at Woodland Dam and Grand Falls Dam. To inform the location and types of potential future fish passage, starting in 2022 the University of Maine will use active telemetry (radio) monitoring to characterize migratory path choice and success at the Woodland and Grand Falls dams. This location and path choice assessment work was identified as a crucial need through a previously funded IWI feasibility project entitled “Exploring Upstream and Downstream Fish Passage Improvements on the Lower St. Croix River”. The project will provide actionable information for the engineering and design of new fish passage at these sites. New fish passage construction is a significant investment (tens of millions of dollars) and is anticipated to result in the return of tens of millions of alewives annually. All data collected through this project will be made available to support evolving restoration plans.





New Brunswick Power, Passamaquoddy Recognition Group Inc., Maine Department of Marine Resources, University of Maine/Maine DSMR, The Nature Conservancy, National Oceanic and Atmospheric Administration Fisheries, US Fish and Wildlife Service, Fisheries and Oceans Canada