Alewife Monitoring on the Bagaduce

Spring in Maine means alewives, a species of river herring, are swimming from the ocean to freshwater ponds and lakes to spawn. These little fish and their yearly migration are at the center of connecting onshore communities and the marine ecosystems on which coastal Maine relies.

173 alewives pass into Walkers Pond during a 30-minute counting period on May 30.

In the Bagaduce Watershed, fishermen and community members like Bailey Bowden, a fisheries activist from Penobscot, are leading alewife restoration and monitoring efforts with help from Maine Center for Coastal Fisheries (MCCF). Volunteers from Penobscot, Sedgwick, and Brooksville have tirelessly worked to count the alewife populations in their communities. Since April 29, an estimated 134,000 alewives have passed through Walkers Pond and 42,000 through Wights Pond.

Mike Thalhauser, MCCF’s Fisheries Science and Leadership Advisor, is helping to coordinate the collection of data on the age, sex, and length of alewives, as well as their food source, zooplankton. Along with partners across the country, Maine Center for Coastal Fisheries is helping to understand current alewife populations within the Bagaduce River and restore other populations where alewives have historically been present. This effort is crucial, as alewives contribute to healthy communities and watersheds in the following ways:

  • Alewives are anadromous, meaning they travel from saltwater to freshwater, connecting habitats and communities.
  • Alewives are key prey for numerous species, notably osprey, seals, eagles, and groundfish.
  • Alewives clean and support our rivers, lakes, and ponds by maintaining a healthy balance of nutrients in the water.
  • Alewives are used as bait for lobster and halibut fisheries.
  • Alewives can offer locally managed commercial fishing opportunities and revenue for towns.
  • Alewives are an integral part of restoring ground fisheries.
Volunteer Counting Alewife

Sarah O’Malley of Blue Hill counts the number of alewives passing into a pond.

Alewives are a reminder of the larger ecosystem; the connectivity of our ocean fisheries in the Gulf of Maine, the surrounding watershed communities, and the numerous habitats in between.

Our work at MCCF would not be possible without the help of community members and other organizations like the Blue Hill Heritage Trust and Maine Coast Heritage Trust. To learn about alewife counting from a volunteer perspective, check out Sarah O’Malley’s blog: Restoring a fishery, one click at a time