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The Cormorant Monitoring and Management Program was established in 2021 to determine the number of double-crested cormorants in the Bonnyville area and assess possible impacts of cormorant activity on nearby lake fisheries.

You can help by sending us the location and size of cormorant colonies and foraging (feeding) groups when you observe them within the Bonnyville monitoring and management area.

Program update

Extensive field activities ran from May to October after the initiation of the program in 2021. Activities included the following:

  • Aerial, stationary, transect, and breeding bird surveys

    Various surveys were conducted in the Bonnyville area to determine:

    • Cormorant numbers
    • Colony locations
    • Foraging areas
    • Cormorant movements
  • In-person colony visits

    In-person colony visits were made to the Muriel, Frog, Lower Mann, and Upper Therien Lake colonies for cormorant diet collection and nest counts.

    Nest count surveys indicate that nest numbers were lower than previous surveys but are within known ranges. Nesting habitat is limited due to water levels and available nesting substrate.

    Boluses (regurgitations) were analyzed to determine what was eaten. Diet analysis of these boluses indicate cormorants feed on a wide range of species, including:

    • Brook stickleback
    • Fathead minnow
    • Spottail shiner
    • White sucker
    • Yellow perch
  • Oiling cormorant eggs

    Oiling cormorant eggs on Muriel and Frog Lake colonies with non-toxic mineral oil was done to humanely reduce cormorant population sizes in the Bonnyville area over time by preventing the eggs from hatching.

  • Fish community assessment

    Fish community assessments of Moose, Muriel, Frog, and Kehiwin Lakes were conducted to assess game fish and minnow populations.

    Summary reports of the fall index netting surveys can be viewed at:

Program activities

  • Determining cormorant numbers in the Bonnyville area.
  • Completing movement surveys to determine where cormorants are coming from and where they are feeding.
  • Collecting and analyzing cormorant diet samples to determine what the birds are feeding on.
  • Identifying other birds that co-nest with cormorants, inventorying and implementing mitigation measures to prevent disturbance to these species.
  • Managing cormorants through egg oiling to reduce the population sizes in the area.
  • Completing fish community assessments on waterbodies in the Moose Lake area to determine number and size of fish and any population trends.
  • Possibly completing angler effort surveys to understand angling pressure and harvest from waterbodies within the study area.

Get involved


If you would like to learn more about the Cormorant Monitoring and Management Program, contact:

Email: [email protected]

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