R-14-04 Variation in Habitat Use by Juvenile River Herring

Karen A. Wilson
Department of Environmental Science
University of Southern Maine

Theodore Willis
University of Southern Maine

Karin Limburg
College of Environmental Science & Forestry
State University of New York

Alewife and blueback herring are sea-run (diadromous) fish that migrate between the ocean and Maine rivers. Once present in large numbers, river herring provided food for humans, other fish, and many wildlife species. Today, while river herring populations are declining throughout their range, in Maine they continue to support local commercial fisheries, primarily for lobster bait.

For these reasons and more, river herring are a target of restoration efforts, which typically focus on enhancing access to freshwater spawning grounds in rivers and lakes. Much less is known about juvenile stages of alewives and blueback herring. What happens to juvenile fish after they leave freshwater can influence growth, behavior, and ultimately whether or not they come back as adults. Limited studies, including preliminary research funded by Sea Grant, suggest that river herring are using estuaries and coastal waters much more than previously assumed, and that individual river herring from the same population may use different habitats. Wilson and her colleagues hope to learn more about where young river herring go and what they eat, using otolith microchemistry, diet analysis, and stable isotope signatures, and provide this information to those who are trying to restore and manage local herring runs.

The team, including University of Southern Maine graduate students Greg Labonte and Amy Webb, are using river herring collected by NOAA Fisheries in trawls of the Penobscot Estuary. Analysis is continuing through 2016.

Two-year project, 2014-2016
Total Sea Grant funds: $76,569