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Understanding the St Croix River Food Web


October 2012 - January 2018


In the past several hundred years, the St. Croix River has experienced considerable fluctuations in management and in ecology. The construction of dams, fluctuating impoundment water levels, increased water temperature, restriction of
upstream and downstream passage, conversion of riverine to lake habitat, introduction of nonindigenous species and industrial pollution represent a causal suite of impacts that have shifted the structure and function of the system. Understanding how these nutrients are assimilated is crucial to understanding the movement of nutrients and the trophic interactions within of lake systems with migratory species. This research will provide a critical assessment of the status of the ecosystem by a) providing a synthesis of species specific passage and habitat requirements and system limitations in the drainage and, b) model the food web to document conditions in the watershed including the seasonal dynamics of water quality.

Project objectives are to:

[1] Concurrent with river herring reintroduction actions, provide a synthesis of life cycle, passage and habitat requirements of all sea‐run and riverine migratory fish species native to the St. Croix River.
[2] Model the food web to better understand conditions in the watershed including the seasonal dynamics of water quality

Research Products and Activities


  • Irish, B., Zydlewski, J., and Cunjak R. (2013) Trophic and Marine Interactions in the St Croix River, Maine. Meeting of the International Joint Commission of the St. Croix Waterway, Calais Maine. INVITED June 24.

Current Staff

Federal Staff: 2

Masters Students: 3

Phd Students: 5

Post Docs: 1

University Staff: 17

5 Year Summary

Students graduated: 29

Scientific Publications: 51

Presentations: 248



Funding Agencies

  • International Joint Commission on St Croix Waterway


Maine Cooperative Fish and Wildlife Research Unit Cooperators

  1. Maine Department of Inland Fisheries and Wildlife
  2. U.S. Fish and Wildlife Service
  3. U.S. Geological Survey
  4. University of Maine
  5. Wildlife Management Institute